ORCID Profile
0000-0002-0881-2906
Current Organisations
Northwestern Polytechnical University
,
UNSW Sydney
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Carbon sequestration science | Nanomaterials | Nanotechnology | Electrochemical energy storage and conversion
Publisher: Elsevier BV
Date: 08-2016
Publisher: Wiley
Date: 21-08-2018
Abstract: Highly efficient electrocatalysts derived from metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) for oxygen reduction reaction (ORR) have been developed. However, the subsequent pyrolysis is often needed owing to their poor intrinsic electrical conductivity, leading to undesirable structure changes and destruction of the original fine structure. Now, hybrid electrocatalysts were formed by self-assembling pristine covalent organic polymer (COP) with reduced graphene oxide (rGO). The electrical conductivity of the hybridized COP/rGO materials is increased by more than seven orders of magnitude (from 3.06×10
Publisher: Wiley
Date: 23-12-2019
Abstract: Rechargeable lithium (Li) metal batteries hold great promise for revolutionizing current energy-storage technologies. However, the uncontrollable growth of lithium dendrites impedes the service of Li anodes in high energy and safety batteries. There are numerous studies on Li anodes, yet little attention has been paid to the intrinsic electrocrystallization characteristics of Li metal and their underlying mechanisms. Herein, a guided growth of planar Li layers, instead of random Li dendrites, is achieved on self-assembled reduced graphene oxide (rGO). In situ optical observation is performed to monitor the morphology evolution of such a planar Li layer. Moreover, the underlying mechanism during electrodeposition/stripping is revealed using ab initio molecular dynamics simulations. The combined experiment and simulation results show that when Li atoms are deposited on rGO, each layer of Li atoms grows along (110) crystallographic plane of the Li crystals because of the fine in-plane lattice matching between Li and the rGO substrate, resulting in planar Li deposition. With this specific topographic characteristic, a highly flexible lithium-sulfur (Li-S) full cell with rGO-guided planar Li layers as the anode exhibits stable cycling performance and high specific energy and power densities. This work enriches the fundamental understanding of Li electrocrystallization without dendrites and provides guidance for practical applications.
Publisher: Wiley
Date: 30-07-2013
DOI: 10.1002/JBM.A.34573
Abstract: Peripheral nerves are often subjected to mechanical stretching, which in excess results in various degrees of impairment of their function. An understanding of the biomechanical behavior of peripheral nerves is important to the prevention of nerve injury during surgical manipulation. Here, in vitro mechanical properties and viscoelastic behavior of human ulnar/median nerves were measured with a tensile tester. In vivo stress and deformation of an ulnar nerve was also examined in continuity during a surgical procedure. Finite element models were developed to determine in vitro and in vivo viscoelastic parameters of the nerves. The results show that in vitro mechanical properties of fresh ulnar nerve are different from those measured in vivo. Several factors that are possibly attributed to the difference were analyzed. The in situ strain of the nerves is one of the major factors that must be considered to obtain accurate strain-stress relationship in the in vivo measurement.
Publisher: Springer Science and Business Media LLC
Date: 05-06-2013
DOI: 10.1038/SREP01810
Publisher: Wiley
Date: 08-12-2016
Publisher: Informa UK Limited
Date: 26-10-2012
Publisher: American Scientific Publishers
Date: 2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2TA01701F
Abstract: High entropy alloys (HEAs) are promising as multifunctional electrocatalysts owing to their inherent compositional and structural complexity and thus the multiple active sites for different reactions.
Publisher: American Chemical Society (ACS)
Date: 26-01-2016
Publisher: Elsevier BV
Date: 2001
Publisher: Wiley
Date: 03-09-2018
Publisher: Elsevier
Date: 2018
Publisher: Elsevier BV
Date: 12-2000
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-02-2009
Abstract: The large-scale practical application of fuel cells will be difficult to realize if the expensive platinum-based electrocatalysts for oxygen reduction reactions (ORRs) cannot be replaced by other efficient, low-cost, and stable electrodes. Here, we report that vertically aligned nitrogen-containing carbon nanotubes (VA-NCNTs) can act as a metal-free electrode with a much better electrocatalytic activity, long-term operation stability, and tolerance to crossover effect than platinum for oxygen reduction in alkaline fuel cells. In air-saturated 0.1 molar potassium hydroxide, we observed a steady-state output potential of –80 millivolts and a current density of 4.1 milli s per square centimeter at –0.22 volts, compared with –85 millivolts and 1.1 milli s per square centimeter at –0.20 volts for a platinum-carbon electrode. The incorporation of electron-accepting nitrogen atoms in the conjugated nanotube carbon plane appears to impart a relatively high positive charge density on adjacent carbon atoms. This effect, coupled with aligning the NCNTs, provides a four-electron pathway for the ORR on VA-NCNTs with a superb performance.
Publisher: Informa UK Limited
Date: 08-03-2016
Publisher: American Chemical Society (ACS)
Date: 17-05-2011
DOI: 10.1021/JP201991J
Publisher: AIP Publishing
Date: 17-05-2022
DOI: 10.1063/5.0087808
Abstract: Solid-state electrical conducting materials can be roughly categorized as superconductors, conductors, and semiconductors, depending on their conducting carriers, resistance, and band structures. This research reports the discovery of super-semiconductors, whose resistivity is 3–10 orders of magnitude lower than conventional semiconductors at room temperature. In addition, there is a transition from a metal state to a super-semiconducting state at near room temperatures, which is accompanied by an increase in hole carrier density and the mobility increase in electrons. For the first time, a hole-dominated carrier metal is observed in nanostructured bimetallic arrays near room temperature, and no other special conditions are required. Such a behavior is due to the generation of hot electrons and holes induced by metal plasmon resonance in the infrared range in the nanostructured bimetallic arrays. Our research empowers metals with semiconductor features and paves the way to realize ultra-low-power metal-based semiconductor devices.
Publisher: Elsevier
Date: 2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5RA25599F
Abstract: Unprotonated l -cysteine is docked on single-vacancy and double-vacancy graphenes doped with transition metals from Sc to Zn. The adsystems exhibit interesting adsorption stability and magnetism.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TA03271J
Abstract: Using consistent-potential DFT calculations, two stable spin states of Fe( ii )N 4 C 10 are identified at ORR-relevant potentials. They exhibit dissimilar behavior for the adsorption of ORR intermediates and distinct ORR activity.
Publisher: Springer Science and Business Media LLC
Date: 19-05-2021
DOI: 10.1038/S41467-021-22392-W
Abstract: The climate-carbon cycle feedback is one of the most important climate- lifying feedbacks of the Earth system, and is quantified as a function of carbon-concentration feedback parameter ( β ) and carbon-climate feedback parameter ( γ ). However, the global climate- lifying effect from this feedback loop (determined by the gain factor, g ) has not been quantified from observations. Here we apply a Fourier analysis-based carbon cycle feedback framework to the reconstructed records from 1850 to 2017 and 1000 to 1850 to estimate β and γ . We show that the β -feedback varies by less than 10% with an average of 3.22 ± 0.32 GtC ppm −1 for 1880–2017, whereas the γ -feedback increases from −33 ± 14 GtC K −1 on a decadal scale to −122 ± 60 GtC K −1 on a centennial scale for 1000–1850. Feedback analysis further reveals that the current lification effect from the carbon cycle feedback is small ( g is 0.01 ± 0.05), which is much lower than the estimates by the advanced Earth system models ( g is 0.09 ± 0.04 for the historical period and is 0.15 ± 0.08 for the RCP8.5 scenario), implying that the future allowable CO 2 emissions could be 9 ± 7% more. Therefore, our findings provide new insights about the strength of climate-carbon cycle feedback and about observational constraints on models for projecting future climate.
Publisher: ASME International
Date: 29-06-2004
DOI: 10.1115/1.1751179
Abstract: The fracture toughness of highly-ordered multi-wall carbon-nanotube-reinforced alumina composites is calculated from experimental data on nanoindentation cracking. A combined analytical and numerical model, using cohesive zone models for both matrix cracking and nanotube crack bridging and accounting for residual stresses, is developed to interpret the indentation results and evaluate the fracture toughness of the composite. Results show that residual stress and nanotube bridging play important roles in the nanocomposite fracture. The contribution to toughness from the nanotube bridging for cracking transverse to the axis of the nanotubes is calculated to be ∼5 MPa-m1/2. From the nanotube bridging law, the nanotube strength and interfacial frictional stress are also estimated and range from 15–25 GPa and 40–200 MPa, respectively. These preliminary results demonstrate that nanotube-reinforced ceramics can exhibit the interfacial debonding/sliding and nanotube bridging necessary to induce nanoscale toughening, and suggest the feasibility of engineering residual stresses, nanotube structure, and composite geometry to obtain high-toughness nanocomposites.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 04-09-2015
Abstract: Seamlessly joint graphene-nanotube 3D architectures were created by one-step CVD for efficient energy conversion and storage.
Publisher: Elsevier BV
Date: 02-2020
Publisher: Springer Science and Business Media LLC
Date: 1999
Publisher: Springer Science and Business Media LLC
Date: 20-11-2015
DOI: 10.1038/NCOMMS9949
Publisher: Springer Science and Business Media LLC
Date: 2016
DOI: 10.1557/ADV.2016.32
Publisher: Wiley
Date: 17-12-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0TA10875H
Abstract: Electrochemical conversion of CO 2 to fuels needs highly active electrocatalysts. We establish the design principles to screen the best catalysts from the family of coordinately unsaturated/saturated transition metal covalent organic frameworks.
Publisher: Elsevier BV
Date: 10-2020
Publisher: Springer Science and Business Media LLC
Date: 14-01-2018
DOI: 10.1557/ADV.2018.51
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CP02014J
Abstract: Defects are common but important in graphene, which could significantly tailor the electronic structures and physical and chemical properties.
Publisher: Elsevier BV
Date: 02-2014
Publisher: Elsevier BV
Date: 02-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6TA10948A
Abstract: Highly active electrocatalysts with a novel bimetallic arrangement of atoms for the oxygen reduction reaction (ORR) are vital for the commercialization of fuel cells.
Publisher: Springer Science and Business Media LLC
Date: 28-03-2022
DOI: 10.1038/S42004-022-00645-Z
Abstract: Electrochemical oxygen reduction provides an eco-friendly synthetic route to hydrogen peroxide (H 2 O 2 ), a widely used green chemical. However, the kinetically sluggish and low-selectivity oxygen reduction reaction (ORR) is a key challenge to electrochemical production of H 2 O 2 for practical applications. Herein, we demonstrate that single cobalt atoms anchored on oxygen functionalized graphene oxide form Co-O-C@GO active centres (abbreviated as Co 1 @GO for simplicity) that act as an efficient and durable electrocatalyst for H 2 O 2 production. This Co 1 @GO electrocatalyst shows excellent electrochemical performance in O 2 -saturated 0.1 M KOH, exhibiting high reactivity with an onset potential of 0.91 V and H 2 O 2 production of 1.0 mg cm −2 h −1 while affording high selectivity of 81.4% for H 2 O 2 . Our combined experimental observations and theoretical calculations indicate that the high reactivity and selectivity of Co 1 @GO for H 2 O 2 electrogeneration arises from a synergistic effect between the O-bonded single Co atoms and adjacent oxygen functional groups (C-O bonds) of the GO present in the Co-O-C active centres.
Publisher: Wiley
Date: 03-10-2023
Abstract: Transparent wood is promising for energy‐saving buildings, but its poor mechanical properties in transverse direction dramatically limit its applications. To resolve the problem, a novel processing technology is developed to fabricate laminated transparent woods. Various kinds of transparent woods are prepared by stacking partially impregnated woods in different styles and then compressing them. The wood template contents in these transparent woods are significantly increased by the partial impregnation compared with traditional full impregnation. The influence of lamination structures on the properties of the transparent woods is also evaluated. As the number of laminate layers increases from one to three, the optical transmittance reduces from ≈70% to 44%, respectively, while the haze increases from 32% to 66%. The isotropy of scatter light distribution could be achieved by controlling lamination structures for more uniformity in indoor illumination. The mechanical properties of the transparent woods are dramatically enhanced, and the highest tensile and flexural strength can reach 134.0 and 192.3 MPa, respectively. Additionally, the direction‐dependence of mechanical strength is reduced by cross‐laminating. The adjustable optical features, excellent mechanical strengths, and low thermal conductivity endow the prepared transparent woods a promising candidate for energy‐efficient buildings applications.
Publisher: Wiley
Date: 09-10-2019
Publisher: Frontiers Media SA
Date: 21-11-2019
Publisher: American Chemical Society (ACS)
Date: 20-03-2012
DOI: 10.1021/AM201796K
Abstract: The adhesion and friction coupling of hierarchical carbon nanotube arrays was investigated with a hierarchical multiscale modeling approach. At device level, vertically aligned carbon nanotube (VA-CNT) arrays with laterally distributed segments on top were analyzed via finite element methods to determine the macroscopic adhesion and friction force coupling. At the nanoscale, molecular dynamics simulation was performed to explore the origin of the adhesion enhancement due to the existence of the laterally distributed CNTs. The results show interfacial adhesion force is drastically promoted by interfacial friction force when a single lateral CNT is being peeled from an amorphous carbon substrate. By fitting with experiments, we find that under shearing loadings the maximum interfacial adhesion force is increased by a factor of ~5, compared to that under normal loadings. Pre-existing surface asperities of the substrate have proven to be the source of generating large interfacial friction, which in turn results in an enhanced adhesion. The critical peeling angles derived from the continuum and nano- levels are comparable to those of geckos and other synthetic adhesives. Our analysis indicates that the adhesion enhancement factor of the hierarchically structured VA-CNT arrays could be further increased by uniformly orienting the laterally distributed CNTs on top. Most importantly, a significant buckling of the lateral CNT at peeling front is captured on the molecular level, which provides a basis for the fundamental understanding of local deformation, and failure mechanisms of nanofibrillar structures. This work gives an insight into the durability issues that prevent the success of artificial dry adhesives.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8MH01441H
Abstract: A self-healing hydrogel with a triple network structure and pressure sensitive photoluminescence for remote force measurement and healing assessment was successfully fabricated.
Publisher: Wiley
Date: 26-02-2018
Publisher: Elsevier BV
Date: 05-2012
Publisher: Elsevier
Date: 2022
Publisher: American Chemical Society (ACS)
Date: 02-08-2018
Publisher: American Scientific Publishers
Date: 08-2012
Publisher: Wiley
Date: 13-03-2020
Publisher: Springer Science and Business Media LLC
Date: 12-09-2016
Publisher: Elsevier BV
Date: 2018
Publisher: IOP Publishing
Date: 13-10-2016
Publisher: American Physical Society (APS)
Date: 24-07-2009
Publisher: Elsevier BV
Date: 02-2014
Publisher: Wiley
Date: 25-09-2009
Publisher: Springer Science and Business Media LLC
Date: 24-02-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0NR03521A
Abstract: An established descriptor Φ can be used to screen and predict highly efficient catalysts based on tuned graphene for the ORR/OER.
Publisher: Informa UK Limited
Date: 30-01-2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2NR04880A
Abstract: Single-atom catalysts (SACs) are promising as efficient electrocatalysts for clean energy technologies such as fuel cells, water splitting, and metal-air batteries. Still, the unsatisfactory loading density and stability of the catalytic active centers limit their applications. Herein, a doping strategy is explored to achieve highly efficient and stable SACs for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The stability, electronic structures, and ORR/OER overpotentials of S-doped transition metal-nitrogen-carbon SAC structures were investigated using first-principles calculation methods. An intrinsic descriptor linking the intrinsic properties of catalysts and the catalytic activity was established for screening the best SACs. The theoretical predictions are well consistent with the experimental results, which provide a theoretical basis for understanding the catalytic mechanism and an approach for the rational design of SACs for clean energy conversion and storage.
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 05-2001
Publisher: American Chemical Society (ACS)
Date: 09-09-2014
DOI: 10.1021/LA502735W
Abstract: The interactions between micrometer-sized particles and substrates in aqueous environment are fundamental to numerous natural phenomena and industrial processes. Here we report a dynamically induced enhancement in adhesion interactions between microparticles and substrates immerged in water, air, and hexane. The dynamic adhesion force was measured by pulling microsized spheres off various substrate (hydrophilic/hydrophobic) surfaces at different retracting velocities. It was observed that when the pull-off velocity varies from 0.02 to 1500 μm/s, there is 100-200% increase in adhesion force in water while it has a 100% increase in nitrogen and hexane. The dynamic adhesion enhancement reduces with increasing effective contact angle defined by the average cosine of wetting angles of the substrates and the particles, and approaches the values measured in dry nitrogen and hexane as the effective contact angle is larger than 90(o). A dynamic model was developed to predict the adhesion forces resulting from this dynamic effect, and the predictions correlate well with the experimental results. The stronger dynamic adhesion enhancement in water is mainly attributed to electrical double layers and the restructuring of water in the contact area between particles and substrates.
Publisher: Elsevier BV
Date: 09-2009
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TA00336A
Abstract: A computational method, based on DFT and electrical double-layer interface models with explicit hydrogen bonding, is developed to accurately predict potential-dependent reaction pathways, catalytic activity, and product selectivity of CO 2 reduction.
Publisher: Elsevier BV
Date: 06-2020
Publisher: American Chemical Society (ACS)
Date: 23-06-2016
Abstract: The structure of A-C type intervariant interface in nonmodulated martensite in the Ni54Mn25Ga21 alloy was studied using high resolution transmission electron microscopy. The A-C interface is between the martensitic variants A and C, each of which has a nanoscale substructure of twin-related lamellae. According to their different thicknesses, the nanoscale lamellae in each variant can be classified into major and minor lamellae. It is the boundaries between these lamellae in different variants that constitute the A-C interface, which is thus composed of major-major, minor-minor, and major-minor lamellar boundaries. The volume fraction of the minor lamellae, λ, plays an important role in the structure of A-C interfaces. For major-major and minor-minor lamellar boundaries, they are symmetrical or asymmetrical tilt boundaries for major-minor boundary, as λ increases, it changes from a symmetrical tilt boundary to two asymmetrical microfacets. Moreover, both lattice and misfit dislocations were observed in the A-C interfaces. On the basis of experimental observations and dislocation theory, we explain how different morphologies of the A-C interface are formed and describe the formation process of the A-C interfaces from λ ≈ 0 to λ ≈ 0.5 in terms of dislocation-boundary interaction, and we infer that low density of interfacial dislocations would lead to high mobility of the A-C interface.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5TC01912E
Abstract: The unique economical design of sulfur and nitrogen co-doped carbon dots with high photoluminescence quantum yield and superior performance for environmental Hg 2+ detection.
Publisher: American Chemical Society (ACS)
Date: 19-11-2021
Abstract: Dry adhesives that combine strong adhesion, high transparency, and reusability are needed to support developments in emerging fields such as medical electrodes and the bonding of electronic optical devices. However, achieving all of these features in a single material remains challenging. Herein, we propose a pressure-responsive polyurethane (PU) adhesive inspired by the octopus sucker. This adhesive not only showcases reversible adhesion to both solid materials and biological tissues but also exhibits robust stability and high transparency (>90%). As the adhesive strength of the PU adhesive corresponds to the application force, adhesion could be adjusted by the preloading force and/or pressure. The adhesive exhibits high static adhesion (∼120 kPa) and 180° peeling force (∼500 N/m), which is far stronger than those of most existing artificial dry adhesives. Moreover, the adhesion strength is effectively maintained even after 100 bonding-peeling cycles. Because the adhesive tape relies on the combination of negative pressure and intermolecular forces, it overcomes the underlying problems caused by glue residue like that left by traditional glue tapes after removal. In addition, the PU adhesive also shows wet-cleaning performance the contaminated tape can recover 90-95% of the lost adhesion strength after being cleaned with water. The results show that an adhesive with a microstructure designed to increase the contribution of negative pressure can combine high reversible adhesion and long fatigue life.
Publisher: American Physical Society (APS)
Date: 30-06-2004
Publisher: Elsevier BV
Date: 04-2018
Publisher: Wiley
Date: 07-06-2014
DOI: 10.1111/JACE.13019
Publisher: American Chemical Society (ACS)
Date: 22-10-2018
Publisher: American Association for the Advancement of Science (AAAS)
Date: 10-10-2008
Abstract: The ability of gecko lizards to adhere to a vertical solid surface comes from their remarkable feet with aligned microscopic elastic hairs. By using carbon nanotube arrays that are dominated by a straight body segment but with curly entangled top, we have created gecko-foot–mimetic dry adhesives that show macroscopic adhesive forces of ∼100 newtons per square centimeter, almost 10 times that of a gecko foot, and a much stronger shear adhesion force than the normal adhesion force, to ensure strong binding along the shear direction and easy lifting in the normal direction. This anisotropic force distribution is due to the shear-induced alignments of the curly segments of the nanotubes. The mimetic adhesives can be alternatively binding-on and lifting-off over various substrates for simulating the walking of a living gecko.
Publisher: Elsevier BV
Date: 07-2004
Publisher: American Chemical Society (ACS)
Date: 24-11-2020
Publisher: Wiley
Date: 08-2012
Publisher: Elsevier BV
Date: 09-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7RA10010H
Abstract: The formation of BCC structure in the melt was the key in TiAl crystalline nucleation, and liquid TiAl alloy completely crystallized at the quenching rate of 0.02 K ps −1 .
Publisher: Springer Science and Business Media LLC
Date: 19-09-2023
Publisher: Elsevier BV
Date: 08-2008
Publisher: Elsevier BV
Date: 08-2003
Publisher: Springer Science and Business Media LLC
Date: 2006
DOI: 10.1557/PROC-978-0978-GG15-04
Abstract: Micromechanics model incorporating with molecular dynamics (MD) simulation is developed to simulate the frictional behavior of carbon nanotube (CNT) arrays in ceramic nanocomposites. MD model is used to compute the interaction force and simulate failure mechanisms of in idual nanotube at atomic length scale. The force and deformation calculated from MD simulation are passed to the continuum model to simulate the interaction between nanotube arrays and AFM tips. The coefficient of friction is determined at different load levels. The simulation shows that the low friction in the thick-wall CNT systems occurs because the stiffer CNTs are more resistant to collapse under the applied loads. The predictions for the coefficient of friction are consistent with nanoscale tests.
Publisher: Elsevier BV
Date: 09-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1TA04327G
Abstract: The electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions has been proposed as a sustainable alternative for nitrogen fixation and ammonia production in environmental and renewable energy fields.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA08144D
Abstract: The controllable synthesis of TiO 2 nanostructures with a conformal and ultrathin graphitic carbon coating is critically desirable for new anode material development for Li-ion batteries.
Publisher: Elsevier BV
Date: 02-2008
Publisher: Elsevier BV
Date: 05-2021
Publisher: Elsevier BV
Date: 09-2019
Publisher: American Astronomical Society
Date: 04-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA11844E
Abstract: Nano-fillet enhances both the stability and mechanical properties of carbon nanotube–graphene junctions synthesized by a templating method.
Publisher: Elsevier BV
Date: 2019
DOI: 10.2139/SSRN.3446987
Publisher: Elsevier BV
Date: 02-2015
Publisher: Wiley
Date: 23-02-2017
Abstract: Covalent organic frameworks (COFs), an emerging class of framework materials linked by covalent bonds, hold potential for various applications such as efficient electrocatalysts, photovoltaics, and sensors. To rationally design COF-based electrocatalysts for oxygen reduction and evolution reactions in fuel cells and metal-air batteries, activity descriptors, derived from orbital energy and bonding structures, are identified with the first-principle calculations for the COFs, which correlate COF structures with their catalytic activities. The calculations also predict that alkaline-earth metal-porphyrin COFs could catalyze the direct production of H
Publisher: Elsevier BV
Date: 02-2004
Publisher: Elsevier BV
Date: 11-2001
Publisher: Springer Science and Business Media LLC
Date: 09-04-2010
Publisher: Springer Science and Business Media LLC
Date: 06-1992
DOI: 10.1007/BF02656284
Publisher: Elsevier BV
Date: 07-2002
Publisher: American Chemical Society (ACS)
Date: 03-06-2020
Publisher: AIP Publishing
Date: 05-2012
DOI: 10.1063/1.4711090
Abstract: Silicon carbide nanowires (NWs) are promising candidates for structural applications owing to their excellent mechanical, thermal, and electronic properties. The effect of amorphous carbon coatings on the mechanical behavior of the nanowires was studied via molecular dynamics methods at room temperature. The results show that the amorphous carbon coatings can shield opening cracks on silicon carbide nanowires, making them damage-tolerant. With increasing the defect size, the tensile strength and fracture energy of uncoated silicon carbide nanowires rapidly decrease however, the properties of coated nanowires maintain nearly constant. Increasing the coating thickness leads to a brittle-to-ductile transition for the nanowires. Careful tailoring of the coatings permits engineering of these nanostructures for higher strength and damage tolerance at submicron scales.
Publisher: Frontiers Media SA
Date: 19-02-2019
Publisher: American Chemical Society (ACS)
Date: 07-03-2014
DOI: 10.1021/NL4047784
Abstract: Substantial differences in charge storage mechanisms exist between dielectric capacitors (DCs) and electrochemical capacitors (ECs), resulting in orders of magnitude difference of stored charge density in them. However, if ionic diffusion, the major charge transport mechanism in ECs, is confined within nanoscale dimensions, the Helmholtz layers and diffusion layers will overlap, resulting in dismissible ionic diffusion. An interesting contradiction between appreciable energy density and unrecognizable ionic diffusion is observed in solid-state capacitors made from reduced graphene oxide films that challenge the fundamental charge storage mechanisms proposed in such devices. A new capacitive model is proposed, which combines the two distinct charge storage mechanisms of DCs and ECs, to explain the contradiction, of high storage capacity yet undetectable ionic diffusion, seen in graphene oxide based supercapacitors.
Publisher: American Chemical Society (ACS)
Date: 03-02-2016
Publisher: ASMEDC
Date: 2007
Abstract: Understanding the structure and properties of metal nanowires is critical for the atomic-scale manipulation, design and application of those materials. Currently, active research on structure and behavior of various metallic nanowires has been carried out by computer simulation. Much experimental work has been done for synthesizing various metal nanowires by many different methods. To experimentally explore the mechanism of the behavior of and the development of structures in the nanowires, it is desirable to have the capability of synthesis various metal nanowires with controlled size, length, uniformity and aspect ratio. It is also desirable to further process those metal nanowires to engineer their properties. In our study, a template assisted fabrication method has been employed to fabricate various metal nanowire arrays, including cobalt, iron and nickel. This fabrication method offers us command over the size and length of the nanowires with excellent uniformity. Heat treatments were used to further process the metal nanowires. The structure of cobalt nanowire array has been investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mechanical properties of the metal nanowire array will be investigated through nanoindentation and atomic force microscopy (AFM).
Publisher: American Chemical Society (ACS)
Date: 23-03-2020
Publisher: Elsevier BV
Date: 11-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TA01821J
Abstract: Na and K-ion batteries are promising energy storage devices at low cost, but their inferior rate and capacity have h ered application. We develop the design principles to screen pseudocapacitive carbon anode materials to create ultrafast batteries.
Publisher: Wiley
Date: 09-03-2017
Abstract: Metal-free electrocatalysts have been extensively developed to replace noble metal Pt and RuO
Publisher: Chinese Chemical Society
Date: 09-5014
Publisher: Wiley
Date: 22-08-2023
Abstract: Pseudocapacitive storage of multivalent ions, especially Ca 2+ , in heteroatom‐doped carbon nanomaterials is promising to achieve both high energy and power densities, but there is the lack of pseudocapacitive theories that enable rational design of the materials for calcium‐ion batteries. Herein, the general design principles are established for the anode materials of the batteries via density functional theory calculations and experimental verifications of a series of heteroatom‐doped graphene as an efficient pseudocapacitive anode. A novel descriptor Φ is proposed to correlate the intrinsic properties of dopants with the pseudocapacitive storage properties of the carbon‐based anode. The design principle and descriptor have the predictive ability to screen out the best dual‐doped graphene anode with 10 times higher Ca 2+ storage capability than that of sole‐doped one, and exceed the current best Ca 2+ storage anode materials.
Publisher: American Chemical Society (ACS)
Date: 15-02-2021
Publisher: Wiley
Date: 28-02-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0RA01885F
Abstract: Build grain boundaries for Al 0.1 CoCrFeNi Σ3(111)[11̄0] HEA and elucidate the deformation behavior under tensile and compressive loading.
Publisher: American Chemical Society (ACS)
Date: 29-04-2020
DOI: 10.1021/JACS.0C03459
Publisher: Elsevier BV
Date: 2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CP04618F
Abstract: Graphene-covered halides are designed as durable and efficient electrocatalysts in acid media. A design principle has been established through the DFT calculations, from which the best catalysts could be predicted for fuel cells.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8RA09122F
Abstract: Ag core–shell nanoparticle is a promising candidate as an efficient and cost-effective electrocatalyst for ORR and OER in fuel cells and metal–air batteries. Shell strain is the intrinsic descriptor to rationalize the electrochemical activity.
Publisher: Wiley
Date: 29-09-2015
Abstract: Oxygen reduction reaction/oxygen evolution reaction (ORR/OER) catalytic activities of p-orbital heteroatom-doped carbon nanomaterials are demonstrated to correlate to the combination of the electron affinity and electronegativity of doping elements, which serves as an activity descriptor for the entire family of p-block element dopants. Such a descriptor has predictive power and enables effective design of new bifunctional catalysts with enhanced ORR/OER activities.
Publisher: Wiley
Date: 24-10-2019
Publisher: Springer Science and Business Media LLC
Date: 12-2010
DOI: 10.1007/BF03353857
Abstract: In this communication, we report a synthetic approach to fabricate Y-junction Co nanowires and Y-junction Cu nanowires by AC electrodeposition using a hierarchically designed anodized aluminum oxide template. Morphology study showe that diameters of the stems and branches of the Y-junction nanowires were about 40 nm and 20 nm respectively. Structural analysis indicates that Co nanowires had a mixture of face-center-cubic and hexagonal-close-packed structures, whereas Cu nanowires had a face-center-cubic structure with a texture. The Y-junction Co nanowires exhibited a longitudinal coercivity of 1300 Oe and remnant magnetization of 56%, which was affected by the growth direction and microstructure. The present method can be extended to other metallic systems and thus provides a simple and efficient way to fabricate Y-junction metal nanowires.
Publisher: American Chemical Society (ACS)
Date: 09-06-2011
DOI: 10.1021/LA200995R
Abstract: In the present work, we have developed a simple but effective method to prepare superlong vertically aligned carbon nanotubes (SLVA-CNT) and epoxy composite membranes, and we have demonstrated that various liquids, including water, hexane, and dodecane, can effectively pass through the SLVA-CNT membranes. These results were confirmed by molecular dynamics simulations. While the mechanical densification was used to further enhance the flow transport through the SLVA-CNT membranes, we developed in this study a magnetic-nanoparticle switching system to turn on and off the flow through the nanotube membrane by simply applying an alternating voltage. The methodologies developed in this study should have a significant implication to the development of various smart membranes for advanced intelligent systems.
Publisher: IOP Publishing
Date: 24-10-2019
Abstract: Nanoimprinting behaviors of copper substrates and double-walled carbon nanotubes with interwall sp 3 bonds are investigated using molecular dynamics simulations. A high-frequency mechanical vibration with various litudes is applied on the carbon nanotube (CNT) mold and copper substrate in different directions. Results show that exciting mechanical resonances both on the CNT and substrate drastically decrease the maximum imprint force and interfacial friction up to 50% under certain litudes. Meanwhile, it is demonstrated that defects occur in the {111} plane in the copper substrate during nanoimprinting. For different CNT array densities, a higher grafting density needs more imprint force to transfer patterns. The maximum imprint force for a large range of CNT array densities can be reduced by vibrational perturbations, while reduction rates depend on the CNT grafting density. This work sheds deep insights into the nanoimprint process at the atomic level, suggesting that vibration perturbation is an effective approach for improving the nanoimprinting accuracy and preventing the fracture of nanopatterns.
Publisher: The Royal Society
Date: 09-2016
Abstract: With millions of years of natural evolution, organisms have achieved sophisticated structures, patterns or textures with complex, spontaneous multifunctionality. Among all the fascinating characteristics observed in biosystems, self-cleaning ability is regarded as one of the most interesting topics in biomimicry because of its potential applications in various fields such as aerospace, energy conversion and biomedical and environmental protection. Recently, in-depth studies have been carried out on various compelling biostructures including lotus leaves, shark skins, butterfly wings and gecko feet. To understand and mimic their self-cleaning mechanisms in artificial structures, in this article, recent progress in self-cleaning techniques is discussed and summarized. Based on the underlying self-cleaning mechanisms, the methods are classified into two categories: self-cleaning with water and without water. The review gives a succinct account of the detailed mechanisms and biomimetic processes applied to create artificial self-cleaning materials and surfaces, and provides some ex les of cutting-edge applications such as anti-reflection, water repellence, self-healing, anti-fogging and micro-manipulators. The prospectives and directions of future development are also briefly proposed.
Publisher: Elsevier BV
Date: 09-2008
Publisher: Elsevier BV
Date: 04-2012
Publisher: Elsevier BV
Date: 05-2020
Publisher: Wiley
Date: 29-05-2012
Abstract: Gecko feet integrate many intriguing functions such as strong adhesion, easy detachment, and self-cleaning. Mimicking gecko toe pad structure leads to the development of new types of fibrillar adhesives useful for various applications. In this Concept article, in addition to the design of adhesive mimics by replicating gecko geometric features, we show a new trend of rational design by adding other physical, chemical, and biological principles on to the geometric merits, for enhancing robustness, responsive control, and durability. Current challenges and future directions are highlighted in the design and nanofabrication of biomimetic fibrillar adhesives.
Publisher: Wiley
Date: 02-07-2023
Abstract: To date, the effect of noble metal (NM) electronic structures on CO 2 reaction activity remains unknown, and explicit screening criteria are still lacking for designing highly efficient catalysts in CO 2 ‐breathing batteries. Herein, by preferentially considering the decomposition of key intermediate Li 2 CO 3 , an intrinsic descriptor constituted of the orbital states and the electronegativity for predicting high‐performance cathode material are discovered. As a demonstration, a series of graphene‐supported noble metals (NM@G) as cathodes are fabricated via a fast laser scribing technique. Consistent with the preliminary prediction, Pd@G exhibits an ultralow overpotential (0.41 V), along with superior cycling performance up to 1400 h. Moreover, the overall thermodynamic reaction pathways on NM@G confirm the reliability of the established intrinsic descriptor. This basic finding of the relationship between the electronic properties of noble metal cathodes and the performance of Li‐CO 2 batteries provides a novel avenue for designing remarkably efficient cathode materials for metal‐CO 2 batteries.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2NR33027J
Abstract: Geckos can run freely on vertical walls and even ceilings. Recent studies have discovered that gecko's extraordinary climbing ability comes from a remarkable design of nature with nanoscale beta-keratin elastic hairs on their feet and toes, which collectively generate sufficiently strong van der Waals force to hold the animal onto an opposing surface while at the same time disengaging at will. Vertically aligned carbon nanotube (VA-CNT) arrays, resembling gecko's adhesive foot hairs with additional superior mechanical, chemical and electrical properties, have been demonstrated to be a promising candidate for advanced fibrillar dry adhesives. The VA-CNT arrays with tailor-made hierarchical structures can be patterned and/or transferred onto various flexible substrates, including responsive polymers. This, together with recent advances in nanofabrication techniques, could offer 'smart' dry adhesives for various potential applications, even where traditional adhesives cannot be used. A detailed understanding of the underlying mechanisms governing the material properties and adhesion performances is critical to the design and fabrication of gecko inspired CNT dry adhesives of practical significance. In this feature article, we present an overview of recent progress in both fundamental and applied frontiers for the development of CNT-based adhesives by summarizing important studies in this exciting field, including our own work.
Publisher: Springer Science and Business Media LLC
Date: 11-2009
Publisher: Springer Science and Business Media LLC
Date: 05-2006
Publisher: Elsevier BV
Date: 12-2017
Publisher: Elsevier BV
Date: 05-2014
Publisher: Springer Science and Business Media LLC
Date: 16-10-2017
Publisher: Wiley
Date: 16-03-2012
Publisher: Elsevier BV
Date: 06-2023
Publisher: IOP Publishing
Date: 14-01-2013
Publisher: IOP Publishing
Date: 31-12-2018
Abstract: Lithium-sulfur (Li-S) batteries hold great promise for the next-generation lithium-ion energy storage devices. A key issue in the Li-S batteries is, however, the dissolving and migrating of the soluble polysulfides during the charge and discharge processes and introducing anchoring materials (AM) in the batteries effectively prevent the problem and improve the cycling stability of the Li-S batteries. Herein, Pmma-XO (X = C, Si, Ge, Sn) monolayers are introduced as AM to confine the lithium polysulfides and their anchoring properties are studied with the density functional theory methods. Particularly, Pmma-SiO and GeO monolayers are studied for the first time, and our calculations show that these two materials are stable semiconductive monolayers with direct-band-gaps and moderate binding with lithium polysulfides Li
Publisher: American Chemical Society (ACS)
Date: 18-07-2018
Abstract: Geckos have one of the world's most efficient reversible adhesion systems. Even walking in dusty conditions, geckos can dislodge up to 80% of contaminants and recover their adhesion capability after walking as few as four steps. Thus far, artificial dry self-cleaning materials inspired by the geckos' hierarchical fibrillar structure have been only able to remove 55% of collected large particle contaminants with 30 steps. Challenges, including low mechanical strength, low stiffness, and short fatigue time keep these materials from being used in practical applications. This study involves the novel fabrication of dry self-cleaning surfaces with a high mechanical performance and an outstanding dry self-cleaning property. Imposing a load-drag-pull process similar to a gecko's foot adhesion process, our biomimetic surfaces could dislodge up to 59% of microparticles (∼8 μm) with as few as five steps. Furthermore, the surface had an excellent screening ability at low temperatures regardless of the surface roughness similarity. The surfaces were also proven to be scratch resistant. The biomimetic surfaces exhibit enhanced dry self-cleaning and mechanical properties and could be promising in applications such as reusable adhesives, biochips, aerospace satellite waste collection, and screening equipment.
Publisher: Elsevier BV
Date: 12-2019
Publisher: Elsevier BV
Date: 10-2000
Publisher: Elsevier BV
Date: 12-2019
Publisher: Springer US
Date: 2008
Publisher: John Wiley & Sons, Inc.
Date: 2001
Publisher: Springer Science and Business Media LLC
Date: 18-11-2014
DOI: 10.1038/NCOMMS6246
Abstract: Monolayer molybdenum disulfide (MoS2) has attracted tremendous attention due to its promising applications in high-performance field-effect transistors, phototransistors, spintronic devices and nonlinear optics. The enhanced photoluminescence effect in monolayer MoS2 was discovered and, as a strong tool, was employed for strain and defect analysis in MoS2. Recently, large-size monolayer MoS2 has been produced by chemical vapour deposition, but has not yet been fully explored. Here we systematically characterize chemical vapour deposition-grown MoS2 by photoluminescence spectroscopy and mapping and demonstrate non-uniform strain in single-crystalline monolayer MoS2 and strain-induced bandgap engineering. We also evaluate the effective strain transferred from polymer substrates to MoS2 by three-dimensional finite element analysis. Furthermore, our work demonstrates that photoluminescence mapping can be used as a non-contact approach for quick identification of grain boundaries in MoS2.
Publisher: Elsevier BV
Date: 05-2020
Publisher: Frontiers Media SA
Date: 08-09-2021
DOI: 10.3389/FNANO.2021.667287
Abstract: Living organisms have evolved, over billions of years, to develop specialized biostructures with switchable adhesion for various purposes including climbing, perching, preying, sensing, and protecting. According to adhesion mechanisms, switchable adhesives can be ided into four categories: mechanically-based adhesion, liquid-mediated adhesion, physically-actuated adhesion and chemically-enhanced adhesion. Mimicking these biostructures could create smart materials with switchable adhesion, appealing for many engineering applications in robotics, sensors, advanced drug-delivery, protein separation, etc. Progress has been made in developing bioinspired materials with switchable adhesion modulated by external stimuli such as electrical signal, magnetic field, light, temperature, pH value, etc. This review will be focused on new advance in biomimetic design and synthesis of the materials and devices with switchable adhesion. The underlying mechanisms, design principles, and future directions are discussed for the development of high-performance smart surfaces with switchable adhesion.
Publisher: Elsevier BV
Date: 08-2002
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4RA04008B
Abstract: Two mechanisms of seamlessly C–C bonded junction formation: (i) CNT growth over the holes that are smaller than 3 nm. (ii) CNT growth inside the holes that are larger than 3 nm.
Publisher: Springer Science and Business Media LLC
Date: 06-04-2015
Abstract: The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out with noble metals (such as Pt) and metal oxides (such as RuO₂ and MnO₂) as catalysts, respectively. However, these metal-based catalysts often suffer from multiple disadvantages, including high cost, low selectivity, poor stability and detrimental environmental effects. Here, we describe a mesoporous carbon foam co-doped with nitrogen and phosphorus that has a large surface area of ∼1,663 m(2) g(-1) and good electrocatalytic properties for both ORR and OER. This material was fabricated using a scalable, one-step process involving the pyrolysis of a polyaniline aerogel synthesized in the presence of phytic acid. We then tested the suitability of this N,P-doped carbon foam as an air electrode for primary and rechargeable Zn-air batteries. Primary batteries demonstrated an open-circuit potential of 1.48 V, a specific capacity of 735 mAh gZn(-1) (corresponding to an energy density of 835 Wh kgZn(-1)), a peak power density of 55 mW cm(-2), and stable operation for 240 h after mechanical recharging. Two-electrode rechargeable batteries could be cycled stably for 180 cycles at 2 mA cm(-2). We also examine the activity of our carbon foam for both OER and ORR independently, in a three-electrode configuration, and discuss ways in which the Zn-air battery can be further improved. Finally, our density functional theory calculations reveal that the N,P co-doping and graphene edge effects are essential for the bifunctional electrocatalytic activity of our material.
Publisher: AIP Publishing
Date: 17-08-2020
DOI: 10.1063/5.0012709
Abstract: Using a polymer-masking approach, we have developed metal-free 2D carbon electrocatalysts based on single-layer graphene with and without punched holes and/or N-doping. A combined experimental and theoretical study on the resultant 2D graphene electrodes revealed that a single-layer graphene sheet exhibited a significantly higher electrocatalytic activity at its edge than that over the surface of its basal plane. Furthermore, the electrocatalytic activity of a single-layer 2D graphene sheet was significantly enhanced by simply punching microholes through the graphene electrode due to the increased edge population for the hole-punched graphene electrode. In a good consistency with the experimental observations, our density function theory calculations confirmed that the introduction of holes into a graphene sheet generated additional positive charge along the edge of the punched holes and hence the creation of more highly active sites for the oxygen reduction reaction. The demonstrated concept for less graphene material to be more electrocatalytically active shed light on the rational design of low-cost, but efficient electrocatalysts from 2D graphene for various potential applications ranging from electrochemical sensing to energy conversion and storage.
Publisher: IOP Publishing
Date: 21-04-2009
DOI: 10.1088/0957-4484/20/19/195703
Abstract: The static and dynamic behaviors of partially charged and end-grafted polyelectrolyte brushes in response to electric fields were investigated by means of molecular dynamics simulation. The results show that the polymer brushes can be partially or fully stretched by applying an external electric field. Moreover, the brushes can switch reversibly from collapsed to stretched states, fully responding to the AC electric stimuli, and the gating response frequency can reach a few hundred MHz. The effects of the grafting density, the charge fraction of the brushes and the strength of the electric field on the average height of the polymer brushes were studied through the simulations.
Publisher: Elsevier BV
Date: 06-2007
Publisher: American Chemical Society (ACS)
Date: 05-04-2018
Publisher: Elsevier BV
Date: 02-2021
Publisher: Wiley
Date: 24-11-2017
Abstract: Covalent organic frameworks (COFs) are promising for catalysis, sensing, gas storage, adsorption, optoelectricity, etc. owning to the unprecedented combination of large surface area, high crystallinity, tunable pore size, and unique molecular architecture. Although COFs are in their initial research stage, progress has been made in the design and synthesis of COF-based electrocatalysis for the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, and CO
Publisher: Elsevier BV
Date: 11-2010
Publisher: American Chemical Society (ACS)
Date: 21-10-2006
DOI: 10.1021/JP064875X
Abstract: As a promising one-dimensional material for building nanodevices, single-wall carbon nanotubes (SWNTs) should be organized into a rational architecture on the substrate surface. In this study, horizontally aligned SWNTs with two alignment modes were synthesized on the same R-plane sapphire wafer by chemical vapor deposition with cationized ferritins as catalysts. In the middle part of the wafer, SWNTs were aligned on the R-plane sapphire in the direction [1101]. At the edge of the wafer, SWNTs were aligned in the tangential direction to the wafer edge. The comparison of these two groups of SWNTs suggests the competition between the two alignment modes and indicates that atomic steps in high density have superior influence on the SWNTs' alignment to the crystal structure on the surface of the sapphire substrate. A "raised-head" growth mechanism model is proposed to explain why catalysts can stay active during the horizontally aligned growth of relatively long SWNTs with the strong interaction between SWNTs and the sapphire substrate.
Publisher: Elsevier BV
Date: 10-2012
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 11-2017
Publisher: Elsevier BV
Date: 10-2013
Publisher: The Royal Society
Date: 13-06-2012
Abstract: Gecko toe pads show strong adhesion on various surfaces yet remain remarkably clean around everyday contaminants. An understanding of how geckos clean their toe pads while being in motion is essential for the elucidation of animal behaviours as well as the design of biomimetic devices with optimal performance. Here, we test the self-cleaning of geckos during locomotion. We provide, to our knowledge, the first evidence that geckos clean their feet through a unique dynamic self-cleaning mechanism via digital hyperextension. When walking naturally with hyperextension, geckos shed dirt from their toes twice as fast as they would if walking without hyperextension, returning their feet to nearly 80 per cent of their original stickiness in only four steps. Our dynamic model predicts that when setae suddenly release from the attached substrate, they generate enough inertial force to dislodge dirt particles from the attached spatulae. The predicted cleaning force on dirt particles significantly increases when the dynamic effect is included. The extraordinary design of gecko toe pads perfectly combines dynamic self-cleaning with repeated attachment/detachment, making gecko feet sticky yet clean. This work thus provides a new mechanism to be considered for biomimetic design of highly reuseable and reliable dry adhesives and devices.
Publisher: American Chemical Society (ACS)
Date: 04-12-2020
Publisher: American Chemical Society (ACS)
Date: 29-10-2013
DOI: 10.1021/LA4023757
Abstract: We report a dynamically induced enhancement in interfacial adhesion between microsized particles and substrates under dry and humid conditions. The adhesion force of soft (polystyrene) and hard (SiO2 and Al2O3) microparticles on soft (polystyrene) and hard (fused silica and sapphire) substrates was measured by using an atomic force microscope with retraction (z-piezo) speed ranging over 4 orders of magnitude. The adhesion is strongly enhanced by the dynamic effect. When the retraction speed varies from 0.02 to 156 μm/s, the adhesion force increases by 10% to 50% in dry nitrogen while it increases by 15% to 70% in humid air. Among the material systems tested, the soft-soft contact systems exhibit the smallest dynamic effect while the hard-hard contacts show the largest enhancement. A dynamic model was developed to predict this dynamic effect, which agrees well with the experimental results. The influence of dynamic factors related to the adhesion enhancement, such as particle inertia, viscoelastic deformations, and crack propagation, was discussed to understand the dynamic enhancement mechanisms.
Publisher: AIP Publishing
Date: 2017
DOI: 10.1063/1.4975042
Abstract: The structures and behaviors of grain boundaries (GBs) have profound effects on the mechanical properties of polycrystalline materials. In this paper, twist GBs in aluminum were investigated with molecular dynamic simulations to reveal their atomic structures, energy and interactions with dislocations. One hundred twenty-six twist GBs were studied, and the energy of all these twist GBs were calculated. The result indicates that & & and & & twist GBs have lower energy than & & twist GBs because of their higher interplanar spacing. In addition, 12 types of & & twist GBs in aluminum were chosen to explore the deformation behaviors. Low angle twist GBs with high density of network structures can resist greater tension because mutually hindering behaviors between partial dislocations increase the twist GB strength.
Publisher: IOP Publishing
Date: 23-03-2016
DOI: 10.1088/0957-4484/27/18/185402
Abstract: Tetracyanoethylene (TCNE), with its strong electron-accepting ability, was used to dope graphene as a metal-free electrocatalyst for the oxygen reduction reaction (ORR). The charge transfer process was observed from graphene to TCNE by x-ray photoelectron spectroscopy and Raman characterizations. Our density functional theory calculations found that the charge transfer behavior led to an enhancement of the electrocatalytic activity for the ORR.
Publisher: Springer Science and Business Media LLC
Date: 13-10-2017
Publisher: American Chemical Society (ACS)
Date: 07-02-2014
DOI: 10.1021/JP410501U
Publisher: Wiley
Date: 23-12-2020
Publisher: Frontiers Media SA
Date: 21-02-2020
Publisher: American Chemical Society (ACS)
Date: 07-2021
Abstract: In this study, we propose a top-down approach for the controlled preparation of undercoordinated Ni-N
Publisher: American Chemical Society (ACS)
Date: 07-12-2019
Publisher: Elsevier BV
Date: 07-2018
Publisher: Elsevier BV
Date: 06-2023
Publisher: American Association for the Advancement of Science (AAAS)
Date: 07-08-2015
Abstract: A review of the recent advances, along with perspectives and challenges, in the fast-growing field of carbon-based electrocatalysts.
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 12-2020
Publisher: American Chemical Society (ACS)
Date: 13-08-2010
DOI: 10.1021/AM100409S
Abstract: With unique hierarchical fibrillar structures on their feet, gecko lizards can walk on vertical walls or even ceilings. Recent experiments have shown that strong binding along the shear direction and easy lifting in the normal direction can be achieved by forming unidirectional carbon nanotube array with laterally distributed tips similar to gecko's feet. In this study, a multiscale modeling approach was developed to analyze friction and adhesion behaviors of this hierarchical fibrillar system. Vertically aligned carbon nanotube array with laterally distributed segments at the end was simulated by coarse grained molecular dynamics. The effects of the laterally distributed segments on friction and adhesion strengths were analyzed, and further adopted as cohesive laws used in finite element analysis at device scale. The results show that the laterally distributed segments play an essential role in achieving high force anisotropy between normal and shear directions in the adhesives. Finite element analysis reveals a new friction-enhanced adhesion mechanism of the carbon nanotube array, which also exists in gecko adhesive system. The multiscale modeling provides an approach to bridge the microlevel structures of the carbon nanotube array with its macrolevel adhesive behaviors, and the predictions from this modeling give an insight into the mechanisms of gecko-mimicking dry adhesives.
Publisher: American Physical Society (APS)
Date: 14-06-2007
Publisher: American Chemical Society (ACS)
Date: 03-05-2012
DOI: 10.1021/LA2043262
Abstract: The development of fuel cells as clean-energy technologies is largely limited by the prohibitive cost of the noble-metal catalysts needed for catalyzing the oxygen reduction reaction (ORR) in fuel cells. A fundamental understanding of catalyst design principle that links material structures to the catalytic activity can accelerate the search for highly active and abundant nonmetal catalysts to replace platinum. Here, we present a first-principles study of ORR on nitrogen-doped graphene in acidic environment. We demonstrate that the ORR activity primarily correlates to charge and spin densities of the graphene. The nitrogen doping and defects introduce high positive spin and/or charge densities that facilitate the ORR on graphene surface. The identified active sites are closely related to doping cluster size and dopant-defect interactions. Generally speaking, a large doping cluster size (number of N atoms >2) reduces the number of catalytic active sites per N atom. In combination with N clustering, Stone-Wales defects can strongly promote ORR. For four-electron transfer, the effective reversible potential ranges from 1.04 to 1.15 V/SHE, depending on the defects and cluster size. The catalytic properties of graphene could be optimized by introducing small N clusters in combination with material defects.
Publisher: MDPI AG
Date: 19-12-2011
DOI: 10.3390/POLYM3042142
Publisher: Elsevier BV
Date: 12-2011
Publisher: American Chemical Society (ACS)
Date: 22-06-2016
Abstract: Study of layered complex oxides emerge as one of leading topics in fundamental materials science because of the strong interplay among intrinsic charge, spin, orbital, and lattice. As a fundamental basis of heteroepitaxial thin film growth, interfacial strain can be used to design materials that exhibit new phenomena beyond their conventional forms. Here, we report a strain-driven self-assembly of bismuth-based supercell (SC) with a two-dimensional (2D) layered structure. With combined experimental analysis and first-principles calculations, we investigated the full SC structure and elucidated the fundamental growth mechanism achieved by the strain-enabled self-assembled atomic layer stacking. The unique SC structure exhibits room-temperature ferroelectricity, enhanced magnetic responses, and a distinct optical bandgap from the conventional double perovskite structure. This study reveals the important role of interfacial strain modulation and atomic rearrangement in self-assembling a layered singe-phase multiferroic thin film, which opens up a promising avenue in the search for and design of novel 2D layered complex oxides with enormous promise.
Publisher: American Chemical Society (ACS)
Date: 16-01-2019
Abstract: We demonstrated an N-doped graphene interface with highly switchable adhesion and robust micromanipulation capability triggered by external electric signals. Upon applying a small dc or ac electrical bias, this nanotextured surface can collect environmental moisture to form a large number of water bridges between the graphene and target surface, which lead to a drastic change in adhesive force. Turning on and off the electrical bias can control this graphene interface as a robust micro/nanomanipulator to pick up and drop off various micro/nano-objects for precise assembling. Molecular dynamics simulation reveals that the electrically induced electric double layer and ordered icelike structures at the graphene-water interface strengthen the water bridges and consequently enhance force switchability. In addition to the micro-/nanomanipulation, this switchable adhesion may have many technical implications such as climbing robots, sensors, microfluidic devices, and advanced drug delivery.
Publisher: Elsevier BV
Date: 04-2021
Publisher: American Chemical Society (ACS)
Date: 09-2019
DOI: 10.1021/ACS.LANGMUIR.9B01852
Abstract: We demonstrate a novel nanotextured graphene micropad that can rapidly harvest water from air to generate microscale water droplets with the desired size in designated positions on demand by simply applying a negative electric bias of -1.5 to -15 V. More interestingly, the water droplets can be reversibly dried nonthermally with the pad at ambient temperature in humid air (∼85% RH) by applying a positive electric bias of +1.5 to +15 V. The harvesting and drying rates on the glass are 2.7 and 1.5 μm
Publisher: American Society of Mechanical Engineers
Date: 13-11-2015
Abstract: In an effort to explore a structure-property relationship of an elastomer, we develop a multi-scale model of a thermoplastic polyurethane (PU) elastomer. A hyperelastic nonlinear constitutive equation of PU is constructed from a molecular simulation and is implemented for obtaining macroscopic mechanical properties. A full-atomic model of the PU, whose polymeric chains consist of hard and soft segments, is built using a commercial molecular modeling code — Materials Studio. The long hard segments are decomposed again into two beads for a better coarse grained (CG) model. The probability distribution functions for bond lengths, angles, and pairs are found among the beads to derive the effective potential functions using Inverse Boltzmann Method (IBM). Using the effective potential functions, a CG Molecular Mechanics (MM) model of the PU is built and run in LAMMPS. Initial IBM-derived effective potentials are iterated through CGMD simulations along with pressure correction to keep the distribution functions, density, and thermodynamic states the same for both models at two different scales. The final model is run with iterated force-fields using isobaric-isochoric ensemble (constant pressure, constant temperature) and validated with six full-atomic radial distribution functions (RDFs) and density from experiment. After building a validated CG model, hyperelastic strain energy functions are constructed from the CGMM simulation results of the PU under volumetric and isochoric deformation at the molecular level in order to develop an equivalent continuum model. Considering energy equivalence between the molecular and continuum models, the material constants for a hyperelastic strain energy function of the PU are determined. The derived parameters are used to predict macroscopic properties bulk, shear, and Young’s moduli, and Poisson’s ratio from volumetric and three-dimensional shear loadings using the multi-scale approach. A coupon test of the PU at a macroscopic level is followed for comparison with the CGMM simulation. By the end of the study, we may answer the following research question: how sensitive are the iterative processes and pressure correction while building the effective CG potentials through inverse Boltzmann method.
Publisher: Wiley
Date: 23-08-2013
Abstract: To replace precious platinum (Pt)-based electrocatalysts for cathodic oxygen reduction reaction (ORR), edge-selectively sulfurized graphene nanoplatelets (SGnP) are synthesized as efficient metal-free electrocatalysts simply by ball-milling pristine graphite in the presence of sulfur (S8 ). The resultant SGnPs exhibit remarkable electrocatalytic activity toward ORR with better tolerance to methanol crossover/CO poisoning effects and longer-term stability than those of pristine graphite and commercial Pt/C electrocatalysts. Edge-Selectively Sulfurized Graphene Nanoplatelets as Efficient Metal-Free Electrocatalysts for Oxygen Reduction Reaction: The Electron Spin Effect.
Publisher: Springer Science and Business Media LLC
Date: 2006
DOI: 10.1557/PROC-975-0975-DD10-09
Abstract: Geckos have extraordinary ability to move on vertical surfaces and ceilings. The secret of the climbing ability stems from their foot pads, a special hierarchical hairy structure. Mimicking such structure would lead to dry adhesives for many applications. Recent experiments showed that the adhesion of multiwalled carbon nanotubes is larger than that of a gecko foot-hair. To explore the adhesive mechanisms of the nanotubes, we have developed a multiscale approach to simulate the adhesion process of carbon nanotubes. A molecular dynamics is used to simulate the deformation and damage of the nanotubes when contacting with a rough surface at atomic scale. A coarse graining method is developed to predict the interactions and adhesion of larger scale nanotube array. The parameters used in the coarse graining method are determined by the detailed molecular dynamics. The preliminary results show that the nanotube bending under pre-applied pressure increases the contact area and therefore enhances the adhesion. The nanotube breakage during pre-loading will reduce the adhesion in post cycles. These results are consistent with the experiments found in literature.
Publisher: Wiley
Date: 07-12-2019
Abstract: Carbon nanomaterials are promising metal-free catalysts for energy conversion and storage, but the catalysts are usually developed via traditional trial-and-error methods. To rationally design and accelerate the search for the highly efficient catalysts, it is necessary to establish design principles for the carbon-based catalysts. Here, theoretical analysis and material design of metal-free carbon nanomaterials as efficient photo-/electrocatalysts to facilitate the critical chemical reactions in clean and sustainable energy technologies are reviewed. These reactions include the oxygen reduction reaction in fuel cells, the oxygen evolution reaction in metal-air batteries, the iodine reduction reaction in dye-sensitized solar cells, the hydrogen evolution reaction in water splitting, and the carbon dioxide reduction in artificial photosynthesis. Basic catalytic principles, computationally guided design approaches and intrinsic descriptors, catalytic material design strategies, and future directions are discussed for the rational design and synthesis of highly efficient carbon-based catalysts for clean energy technologies.
Start Date: 03-2024
End Date: 02-2031
Amount: $35,000,000.00
Funder: Australian Research Council
View Funded Activity