ORCID Profile
0000-0001-5393-2301
Current Organisations
The Hong Kong Polytechnic University
,
Curtin University
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Publisher: Wiley
Date: 16-12-2020
Publisher: American Chemical Society (ACS)
Date: 28-09-2023
Publisher: Elsevier BV
Date: 04-2023
Publisher: AIP Publishing
Date: 03-2022
DOI: 10.1063/5.0083059
Abstract: Exploring effective, facile, and universal tuning strategies to optimize material physicochemical properties and catalysis processes is critical for many sustainable energy systems, but still challenging. Herein, we succeed to introduce tensile strain into various perovskites via a facile thermochemical reduction method, which can greatly improve material performance for the bottleneck oxygen-evolving reaction in water electrolysis. As an ideal proof-of-concept, such a chemical-induced tensile strain turns hydrophobic Ba5Co4.17Fe0.83O14-δ perovskite into the hydrophilic one by modulating its solid–liquid tension, contributing to its beneficial adsorption of important hydroxyl reactants as evidenced by fast operando spectroscopy. Both surface-sensitive and bulk-sensitive absorption spectra show that this strategy introduces oxygen vacancies into the saturated face-sharing Co-O motifs of Ba5Co4.17Fe0.83O14-δ and transforms such local structures into the unsaturated edge-sharing units with positive charges and enlarged electrochemical active areas, creating a molecular-level hydroxyl pool. Theoretical computations reveal that this strategy well reduces the thermodynamic energy barrier for hydroxyl adsorption, lowers the electronic work function, and optimizes the charge/electrostatic potential distribution to facilitate the electron transport between active sites and hydroxyl reactants. Also, this strategy is reliable for other single, double, and Ruddlesden–Popper perovskites. We believe that this finding will enlighten rational material design and in-depth understanding for many potential applications.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2NR06665C
Abstract: A heterogeneous single-cluster catalyst Ni100-Fe 4 S 4 via bio-inspired design strategy exhibits excellent theoretical CO 2 electroreduction performance.
Publisher: Research Square Platform LLC
Date: 13-07-2021
DOI: 10.21203/RS.3.RS-670823/V1
Abstract: Improving the catalytic efficiency of platinum (Pt) for hydrogen evolution reaction (HER) is crucial for water splitting technologies, and hydrogen spillover has emerged as a new frontier in designing the binary-component Pt/support HER electrocatalysts. However, such binary catalysts always suffer from long reaction pathway, undesirable interfacial barrier, and complicated synthesis processes. Here we report a single-phase complex oxide La 2 Sr 2 PtO 7+δ as a high-performance HER electrocatalysts in acidic media via a unique atomic-scale hydrogen spillover effect between multifunctional catalytic sites. With insights from theoretical calculations, a possible synergistic mechanism involving the hydrogen spillover channel from O La site→La-Pt bridge site→Pt site is proposed namely, the O La site enriches proton, the La-Pt bridge site with thermo-neutral H* adsorption facilitates the hydrogen spillover and H 2 generation, and Pt site favors the final H 2 desorption. Benefiting from such unusual phenomenon, the resulting La 2 Sr 2 PtO 7+δ exhibits an exceptional HER electrode activity with low overpotential of 13 mV at 10 mA cm − 2 and small Tafel slope of 22 mV dec − 1 , and significantly enhanced intrinsic activity and durability than commercial Pt black catalyst.
Publisher: Elsevier BV
Date: 08-2020
Publisher: Elsevier BV
Date: 07-2023
Publisher: American Chemical Society (ACS)
Date: 11-12-2020
Publisher: Wiley
Date: 12-08-2019
Abstract: Oxygen evolution reaction (OER) is crucial in many renewable electrochemical technologies including regenerative fuel cells, rechargeable metal-air batteries, and water splitting. It is found that abundant active sites with favorable electronic structure and high electrical conductivity play a dominant role in achieving high electrocatalytic efficiency of perovskites, thus efficient strategies need to be designed to generate multiple beneficial factors for OER. Here, highlighted is an unusual super-exchange effect in ferromagnetic perovskite oxide to optimize active sites and enhance electrical conductivity. A systematic exploration about the composition-dependent OER activity in SrCo
Publisher: Elsevier BV
Date: 08-2023
Publisher: Springer Science and Business Media LLC
Date: 02-2018
Publisher: American Chemical Society (ACS)
Date: 10-2018
Publisher: Elsevier BV
Date: 08-2018
Publisher: AIP Publishing
Date: 03-2021
DOI: 10.1063/5.0033912
Abstract: Perovskite oxides are of particular interest for the oxygen evolution reaction (OER) due to their high intrinsic activity. However, low surface area and nonpores in bulk phase generally limit the mass transport and thereby result in unsatisfactory mass activity. Herein, we propose a “molecular-level strategy” with the simultaneous modulation of the ordered pores on the oxygen-deficient sites along with sulfur (S) substitution on oxygen sites at the molecular level to boost the mass transport behavior of perovskite electrocatalyst for enhanced mass activity. As a proof of concept, the elaborately designed brownmillerite oxide Sr2Co1.6Fe0.4O4.8S0.2 (S-BM-SCF) shows approximately fourfold mass activity enhancement in 1 M KOH compared with the pristine SrCo0.8Fe0.2O3-δ (SCF) perovskite. Comprehensive experimental results, in combination with theoretical calculations, demonstrate that the intrinsic molecular-level pores in the brownmillerite structure can facilitate reactive hydroxyl ion (OH−) uptake into the oxygen-vacant sites and that S doping further promotes OH− adsorption by electronic structure modulation, thus accelerating mass transport rate. Meanwhile, the S-BM-SCF can significantly weaken the resistance of O2 desorption on the catalyst surface, facilitating the O2 evolution. This work deepens the understanding of how mass transport impacts the kinetics of the OER process and opens up a new avenue to design high-performance catalysts on the molecular level.
Publisher: Wiley
Date: 03-12-2022
DOI: 10.1002/CEY2.156
Abstract: Molybdenum carbide (Mo x C) with variable phase structure possesses flexible hydrogen‐binding energy (HBE), which is a promising hydrogen evolution reaction (HER) catalyst. Herein, a hybrid multiphase Mo x C freestanding film coupled with Co 3 Mo (CM/Mo x C@NC) is synthesized through the electrospinning method supplemented by the heteroatom incorporation. CM/Mo x C@NC surpasses its pure phase counterparts and exhibits remarkable catalytic activity at 114 mV to deliver a current density of 10 mA cm −2 in acid, which is among the first‐rate level performance reported for Mo x C‐based catalysts. The subsequent ex situ and in situ characterizations reveal a phase transition mechanism based on self‐catalysis that CoO x depletes the coordinated C of α‐MoC via the interaction, which realizes the assembly of weak HBE α‐MoC and strong HBE β‐Mo 2 C, and the enhanced utilization of active materials as well. The multiple structures with optimal HBE are in favor of the stepwise reactions of HER, as the study of the correlation between HBE and phase structure revealed. This study discloses the underlying phase transition mechanism and highlights the HBE–structure relationship that should be considered for catalyst design.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9TA06020K
Abstract: Here, we use an electrospinning method to control the crystal structure, electronic structure and microstructure of catalysts simultaneously.
Publisher: Springer Science and Business Media LLC
Date: 21-08-2019
DOI: 10.1038/S41467-019-11847-W
Abstract: Facile and reliable screening of cost-effective, high-performance and scalable electrocatalysts is key for energy conversion technologies such as water splitting. ABO 3- δ perovskites, with rich constitutions and structures, have never been designed via activity descriptors for critical hydrogen evolution reaction (HER). Here, we apply coordination rationales to introduce A-site ionic electronegativity (AIE) as an efficient unifying descriptor to predict the HER activities of 13 cobalt-based perovskites. Compared with A-site structural or thermodynamic parameter, AIE endows the HER activity with the best volcano trend. (Gd 0.5 La 0.5 )BaCo 2 O 5.5+ δ predicted from an AIE value of ~2.33 exceeds the state-of-the-art Pt/C catalyst in electrode activity and stability. X-ray absorption and computational studies reveal that the peak HER activities at a moderate AIE value of ~2.33 can be associated with the optimal electronic states of active B-sites via inductive effect in perovskite structure (~200 nm depth), including Co valence, Co-O bond covalency, band gap and O 2 p -band position.
Publisher: Wiley
Date: 26-08-2021
Abstract: Corner‐sharing oxides usually suffer from structural reconstruction during the bottleneck oxygen‐evolution reaction (OER) in water electrolysis. Therefore, introducing dynamically stable active sites in an alternative structure is urgent but challenging. Here, 1D 5H‐polytype Ba 5 Bi 0.25 Co 3.75 FeO 14− δ oxide with face‐sharing motifs is identified as a highly active and stable candidate for alkaline OER. Benefiting from the stable face‐sharing motifs with three couples of combined bonds, Ba 5 Bi 0.25 Co 3.75 FeO 14− δ can maintain its local structures even under high OER potentials as evidenced by fast operando spectroscopy, contributing to a negligible performance degradation over 110 h. Besides, the higher Co valence and smaller orbital bandgap in Ba 5 Bi 0.25 Co 3.75 FeO 14− δ endow it with a much better electron transport ability than its corner‐sharing counterpart, leading to a distinctly reduced overpotential of 308 mV at 10 mA cm −2 in 0.1 m KOH. Further mechanism studies show that the short distance between lattice‐oxygen sites in face‐sharing Ba 5 Bi 0.25 Co 3.75 FeO 14− δ can accelerate the deprotonation step (*OOH + OH − = *OO + H 2 O + e − ) via a steric inductive effect to promote lattice‐oxygen participation. In this work, not only is a new 1D face‐sharing oxide with impressive OER performance discovered, but also a rational design of dynamic stable and active sites for sustainable energy systems is inaugurated.
Publisher: Wiley
Date: 26-02-2018
Publisher: Elsevier BV
Date: 10-2021
Publisher: Wiley
Date: 17-06-2021
Abstract: Single‐phase perovskite oxides that contain nonprecious metals have long been pursued as candidates for catalyzing the oxygen evolution reaction, but their catalytic activity cannot meet the requirements for practical electrochemical energy conversion technologies. Here a cation deficiency‐promoted phase separation strategy to design perovskite‐based composites with significantly enhanced water oxidation kinetics compared to single‐phase counterparts is reported. These composites, self‐assembled from perovskite precursors, comprise strongly interacting perovskite and related phases, whose structure, composition, and concentration can be accurately controlled by tailoring the stoichiometry of the precursors. The composite catalyst with optimized phase composition and concentration outperforms known perovskite oxide systems and state‐of‐the‐art catalysts by 1–3 orders of magnitude. It is further demonstrated that the strong interfacial interaction of the composite catalysts plays a key role in promoting oxygen ionic transport to boost the lattice‐oxygen participated water oxidation. These results suggest a simple and viable approach to developing high‐performance, perovskite‐based composite catalysts for electrochemical energy conversion.
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 06-2020
Publisher: Wiley
Date: 22-09-2023
Abstract: Producing indispensable hydrogen and oxygen for social development via water electrolysis shows more prospects than other technologies. Although electrocatalysts have been explored for centuries, a universal activity descriptor for both hydrogen‐evolving (HER) and oxygen‐evolving reactions (OER) has not been developed. Moreover, a unifying concept has not been established to simultaneously understand HER/OER mechanisms. Here, we rationally bridge the relationships between HER/OER activities in three common electrolytes and over 10 representative material properties on 12 3 d ‐metal‐based model oxides through statistical methodologies. Orbital charge‐transfer energy (Δ) can serve as an ideal universal descriptor, where a neither too large nor too small Δ (∼1 eV) with optimal electron‐cloud density around Fermi level affords the best activities, fulfilling Sabatier's principle. Systematic experiments and computations unravel that pristine oxide with Δ ≈ 1 eV possesses metal‐like high‐valence configurations and active lattice‐oxygen sites to help adsorb key protons in HER and induce lattice‐oxygen participation in OER, respectively. After reactions, partially generated metals in HER and high‐valence hydroxides in OER dominate proton adsorption and couple with pristine lattice‐oxygen activation, respectively. These can be successfully rationalized by the unifying orbital charge‐transfer theory. This work provides the foundation of rational material design and mechanism understanding for many potential applications. This article is protected by copyright. All rights reserved
Publisher: Springer Science and Business Media LLC
Date: 10-03-2021
DOI: 10.1038/S41586-021-03264-1
Abstract: One challenge for the commercial development of solid oxide fuel cells as efficient energy-conversion devices is thermo-mechanical instability. Large internal-strain gradients caused by the mismatch in thermal expansion behaviour between different fuel cell components are the main cause of this instability, which can lead to cell degradation, delamination or fracture
Publisher: American Chemical Society (ACS)
Date: 08-05-2020
Publisher: Springer Science and Business Media LLC
Date: 28-01-2021
DOI: 10.1038/S41467-021-20960-8
Abstract: Electrochemical CO 2 reduction (ECR) is highly attractive to curb global warming. The knowledge on the evolution of catalysts and identification of active sites during the reaction is important, but still limited. Here, we report an efficient catalyst (Ag-D) with suitable defect concentration operando formed during ECR within several minutes. Utilizing the powerful fast operando X-ray absorption spectroscopy, the evolving electronic and crystal structures are unraveled under ECR condition. The catalyst exhibits a ~100% faradaic efficiency and negligible performance degradation over a 120-hour test at a moderate overpotential of 0.7 V in an H-cell reactor and a current density of ~180 mA cm −2 at −1.0 V vs. reversible hydrogen electrode in a flow-cell reactor. Density functional theory calculations indicate that the adsorption of intermediate COOH could be enhanced and the free energy of the reaction pathways could be optimized by an appropriate defect concentration, rationalizing the experimental observation.
Publisher: Springer Science and Business Media LLC
Date: 09-11-2020
DOI: 10.1038/S41467-020-19433-1
Abstract: The state-of-the-art active HER catalysts in acid media (e.g., Pt) generally lose considerable catalytic performance in alkaline media mainly due to the additional water dissociation step. To address this issue, synergistic hybrid catalysts are always designed by coupling them with metal (hydro)oxides. However, such hybrid systems usually suffer from long reaction path, high cost and complex preparation methods. Here, we discover a single-phase HER catalyst, SrTi 0.7 Ru 0.3 O 3-δ (STRO) perovskite oxide highlighted with an unusual super-exchange effect, which exhibits excellent HER performance in alkaline media via atomic-scale synergistic active centers. With insights from first-principles calculations, the intrinsically synergistic interplays between multiple active centers in STRO are uncovered to accurately catalyze different elementary steps of alkaline HER namely, the Ti sites facilitates nearly-barrierless water dissociation, Ru sites function favorably for OH* desorption, and non-metal oxygen sites (i.e., oxygen vacancies/lattice oxygen) promotes optimal H* adsorption and H 2 desorption.
Publisher: Elsevier BV
Date: 12-2023
Publisher: Wiley
Date: 25-08-2022
Abstract: Corner‐sharing and edge‐sharing networks are the two most important material genomes. Inspired by the efficient electron transport capacity of corner‐sharing structures and the low steric hindrance of edge‐sharing units, an attempt is made to exert both merits by combining these two networks. Here, a unique self‐assembled hybrid SrCo 0.55 Fe 0.5 O 3‐ δ nanorod composed of a corner‐sharing SrCo 0.5 Fe 0.5 O 3‐ δ phase and edge‐sharing Co 3 O 4 structure is synthesized through a Co‐site enrichment method, which exhibits the low overpotentials of 310 and 290 mV at 10 mA cm –2 for oxygen‐evolving reaction in 0.1 m and 1.0 m KOH, respectively. This efficiency is attributed to the high Co valence with strong CoO covalence and the short distance between CoCo/Fe metal active sites in hybrid nanorods, realizing a synergistic benefit. Combined multiple operando/ex situ characterizations and computational studies show that the edge‐sharing units in hybrid nanorods can help facilitate the deprotonation step of lattice oxygen mechanism (LOM) while the corner‐sharing motifs can accelerate the electron transport during LOM processes, triggering an unusual lattice‐oxygen activation. This methodology of combining important material structural genomes can offer meaningful insights and guidance for various catalytic applications.
Publisher: Springer Science and Business Media LLC
Date: 05-09-2022
Publisher: Elsevier BV
Date: 12-2021
Publisher: Wiley
Date: 29-01-2022
Abstract: A high‐performance cathode of a protonic ceramic fuel cell (PCFC) should possess excellent oxygen reduction reactivity, high proton/oxygen‐ion/electron conductivity, and sufficient operational stability, thus requiring a delicate tuning of both the bulk and surface properties of the electrode material. Although surface modification of perovskites with nanoparticles from reducing‐atmosphere exsolution has been demonstrated effective at improving the electrochemical anodic oxidation, such nanoparticles would easily re‐incorporate into the perovskite lattice causing a big challenge for their application as a cathode. Here, a durable perovskite‐based nanocomposite cathode for PCFCs is reported, which is facilely prepared via the exsolution of nanoparticles in an oxidizing atmosphere. Through composition and cation nonstoichiometry manipulation, a precursor with the nominal composition of Ba 0.95 (Co 0.4 Fe 0.4 Zr 0.1 Y 0.1 ) 0.95 Ni 0.05 O 3−δ (BCFZYN‐095) is designed, synthesized, and investigated, which, upon calcination, gives rise to the formation of a perovskite‐based nanocomposite comprising a major perovskite phase and a minor NiO phase enriched on the perovskite surface. The major perovskite phase enabled by the proper cation nonstoichiometry manipulation promotes bulk proton conduction while the NiO nanoparticles facilitate the oxygen surface exchange process, leading to a superior cathodic performance with a maximum peak power density of 1040 mW cm −2 at 650 °C and excellent operational stability of 400 h at 550 °C.
Publisher: Wiley
Date: 27-06-2023
Abstract: The efficiency of hydrogen evolution reaction (HER) electrocatalysts under acidic conditions is largely determined by the equilibrium of hydrogen adsorption/desorption on the catalyst surface. A promising strategy for enhancing the performance of multimetal‐supported HER electrocatalysts is the utilization of hydrogen spillover. However, current heterostructured catalysts often present challenges such as high interfacial transport barriers, extended reaction paths, and intricate synthesis processes. Addressing these limitations, a novel orthorhombic SrHf 1− x Ru x O 3− δ perovskite oxide is proposed as an exemplary model for an atomic‐level configuration design strategy. This material exhibits a unique synergistic effect of multiple atomic‐level catalytic sites between Hf/Ru pairs, overcoming the aforementioned challenges. This study presents a new cooperative mechanism for HER, consisting of three steps: proton adsorption on the Hf site, hydrogen migration via a strong O‐bridge site, and H 2 detachment from the Ru active site. The high conductivity and unusual charge redistribution within the Hf‐O‐Ru structure further enhance the specific acidic HER activity of SrHf 1− x Ru x O 3− δ . This research paves the way for designing high‐performance HER catalysts for acidic media, leveraging hydrogen spillover and atomic‐scale configurations. The findings have significant implications for the development of efficient, cost‐effective, and environmentally friendly hydrogen production technologies.
Publisher: Wiley
Date: 04-08-2021
Abstract: Reversible protonic ceramic cells (RePCCs) can facilitate the global transition to renewable energy sources by providing high efficiency, scalable, and fuel‐flexible energy generation and storage at the grid level. However, RePCC technology is limited by the lack of durable air electrode materials with high activity toward the oxygen reduction/evolution reaction and water formation/water‐splitting reaction. Herein, a novel nanocomposites concept for developing bifunctional RePCC electrodes with exceptional performance is reported. By harnessing the unique functionalities of nanoscale particles, nanocomposites can produce electrodes that simultaneously optimize reaction activity in both fuel cell/electrolysis operations. In this work, a nanocomposite electrode composed of tetragonal and Ruddlesden–Popper (RP) perovskite phases with a surface enriched by CeO 2 and NiO nanoparticles is synthesized. Experiments and calculations identify that the RP phase promotes hydration and proton transfer, while NiO and CeO 2 nanoparticles facilitate O 2 surface exchange and O 2‐ transfer from the surface to the major perovskite. This composite also ensures fast (H + /O 2‐ /e ‐ ) triple‐conduction, thereby promoting oxygen reduction/evolution reaction activities. The as‐fabricated RePCC achieves an excellent peak power density of 531 mW cm ‐2 and an electrolysis current of −364 mA cm ‐2 at 1.3 V at 600 °C, while demonstrating exceptional reversible operation stability of 120 h at 550 °C.
Publisher: Wiley
Date: 26-03-2018
Abstract: Because of their structural and compositional flexibility, perovskite oxides represent an attractive alternative electrocatalyst class to precious metals for the oxygen reduction reaction (ORR) an important reaction in fuel cells and metal-air batteries. Partial replacement of the original metal cation with another cation, namely, doping, can be used to tailor the ORR activity of perovskite, for which a metal has been exclusively used as the dopant component in the past. Herein, phosphorus is proposed as a non-metal dopant for the cation site to develop a new perovskite family with the formula of La
Publisher: American Chemical Society (ACS)
Date: 20-07-2021
Publisher: Springer Science and Business Media LLC
Date: 14-08-2017
DOI: 10.1038/NPHYS4208
Publisher: American Chemical Society (ACS)
Date: 10-12-2021
Abstract: Electrochemical CO
Publisher: Springer Science and Business Media LLC
Date: 24-04-2020
DOI: 10.1038/S41467-020-15873-X
Abstract: The development of oxygen evolution reaction (OER) electrocatalysts remains a major challenge that requires significant advances in both mechanistic understanding and material design. Recent studies show that oxygen from the perovskite oxide lattice could participate in the OER via a lattice oxygen-mediated mechanism, providing possibilities for the development of alternative electrocatalysts that could overcome the scaling relations-induced limitations found in conventional catalysts utilizing the adsorbate evolution mechanism. Here we distinguish the extent to which the participation of lattice oxygen can contribute to the OER through the rational design of a model system of silicon-incorporated strontium cobaltite perovskite electrocatalysts with similar surface transition metal properties yet different oxygen diffusion rates. The as-derived silicon-incorporated perovskite exhibits a 12.8-fold increase in oxygen diffusivity, which matches well with the 10-fold improvement of intrinsic OER activity, suggesting that the observed activity increase is dominantly a result of the enhanced lattice oxygen participation.
Publisher: Wiley
Date: 04-05-2020
Publisher: Wiley
Date: 03-08-2021
Abstract: Crystalline, amorphous, and crystalline–amorphous materials have become three important electrode materials for the bottleneck oxygen‐evolving reaction (OER) in the promising hydrogen‐producing technology of water splitting. With the rapid development of in situ/ex situ characterizations, the understanding of active sites in electrocatalysts has been deepened via the structure–activity/stability relationships extracted from the observations on catalysts during/after the OER. Herein, the origins of changes in initial crystalline, amorphous, and crystalline–amorphous materials during/after the OER are systematically analyzed and the underlying variation effects on catalyst activity and stability are discussed based on recent representative studies, aiming at guiding OER catalyst design in the future.
Publisher: Springer Science and Business Media LLC
Date: 11-2017
Publisher: Wiley
Date: 30-11-2020
Publisher: Elsevier BV
Date: 05-2023
Publisher: Wiley
Date: 11-03-2022
Abstract: Combining noble metals with nonnoble metals is an attractive strategy to balance the activity and cost of electrocatalysts. However, a guiding principle for selecting suitable nonnoble metals is still lacking. Herein, a thorough mechanistic study on the platform oxygen evolution reaction (OER) electrocatalyst of Ir@Co 3 O 4 to deeply understand the synergy between Ir and Co 3 O 4 for the boosted OER has been carried out. It is demonstrated that the pseudocapacitive feature of Co 3 O 4 plays a key role in accumulating sufficient positive charge [ Q ], while the Ir sites are responsible for achieving a high reaction order (β), synergistically contributing to the high OER activity of Ir@Co 3 O 4 through the rate law equation. Specifically, Ir@Co 3 O 4 displays a low overpotential of 280 mV at 10 mA cm −2 with a small Ir loading of 1.4 wt%. Ir@Co 3 O 4 is further applied to Zn‐air batteries, which enables a low charging potential and thus alleviates the oxidative corrosion of the air electrode, leading to improved cycle stability of 210 h at 20 mA cm −2 . This work demonstrates that anchoring active noble metal sites (for high β) on pseudocapacitive supports (for high [ Q ]) is highly favorable to the OER process, providing a clear guidance for boosting the utilization of noble metals in electrocatalysis.
Publisher: American Chemical Society (ACS)
Date: 26-11-2021
DOI: 10.26434/CHEMRXIV-2021-09486
Abstract: An in-depth understanding of the physicochemical properties of nanorods during the initial growth process has a profound impact on the rational design of high-performance nanorods catalysts. Herein, we conducted a systematic DFT study on the transition metal Co, Ni and alloyed nanoclusters/rods systems to simulate an atomic process from the initial nanoclusters growth to nanorods/wires. We found that the highly active sites of nanorods depend on an interesting electrostatic phenomenon. The surface electrostatic potential analysis shows that all nanoclusters and nanorods structures have formed σ-hole. Unlike nanoclusters, the σ-hole only appears at terminal sites in nanorods, called terminal σ-hole. The elemental composition in nanorods has a certain influence on the maximal surface electrostatic potential (VS,max) i.e., terminal σ-hole. Interestingly, we found that the terminal σ-hole formed in nanorods is generally higher in magnitude than smaller nanoclusters. First-principle calculations show that terminal σ-hole is closely related to the physicochemical activities of nanorods. For ex le, the work function of the directions forming terminal σ-hole is smaller than other directions. More interestingly, we found that in almost all nanorods, compared with other atoms, the d-orbital of the atoms forming terminal σ‑hole shifts close to the Fermi level and exhibits a shallower d-band center, showing higher chemical activity. In short, it is the first time that we discovered terminal σ-hole in nanorods, explained the theoretical basis of terminal σ-hole in nanorod systems, and provided theoretical guidance for the rational design of high-performance nanorods catalysts.
Publisher: Wiley
Date: 09-07-2023
DOI: 10.1002/EEM2.12660
Abstract: For protonic ceramic fuel cells, it is key to develop material with high intrinsic activity for oxygen activation and bulk proton conductivity enabling water formation at entire electrode surface. However, a higher water content which benefitting for the increasing proton conductivity will not only dilute the oxygen in the gas, but also suppress the O 2 adsorption on the electrode surface. Herein, a new electrode design concept is proposed, that may overcome this dilemma. By introducing a second phase with high‐hydrating capability into a conventional cobalt‐free perovskite to form a unique nanocomposite electrode, high proton conductivity/concentration can be reached at low water content in atmosphere. In addition, the hydronation creates additional fast proton transport channel along the two‐phase interface. As a result, high protonic conductivity is reached, leading to a new breakthrough in performance for proton ceramic fuel cells and electrolysis cells devices among available air electrodes.
Publisher: Elsevier BV
Date: 06-2018
Publisher: Elsevier BV
Date: 04-2018
Publisher: Elsevier BV
Date: 11-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1TA10652J
Abstract: BaCe 0.16 Y 0.04 Fe 0.8 O 3− δ nanocomposite cathode exhibits excellent activity and stability for ORR in PCFCs due to the strong interaction between phase components, optimized dual-phase composition and well-balanced proton and oxygen ion conductivity.
Publisher: Springer Science and Business Media LLC
Date: 04-03-2022
DOI: 10.1038/S41467-022-28843-2
Abstract: Improving the catalytic efficiency of platinum for the hydrogen evolution reaction is valuable for water splitting technologies. Hydrogen spillover has emerged as a new strategy in designing binary-component Pt/support electrocatalysts. However, such binary catalysts often suffer from a long reaction pathway, undesirable interfacial barrier, and complicated synthetic processes. Here we report a single-phase complex oxide La 2 Sr 2 PtO 7+δ as a high-performance hydrogen evolution electrocatalyst in acidic media utilizing an atomic-scale hydrogen spillover effect between multifunctional catalytic sites. With insights from comprehensive experiments and theoretical calculations, the overall hydrogen evolution pathway proceeds along three steps: fast proton adsorption on O site, facile hydrogen migration from O site to Pt site via thermoneutral La-Pt bridge site serving as the mediator, and favorable H 2 desorption on Pt site. Benefiting from this catalytic process, the resulting La 2 Sr 2 PtO 7+δ exhibits a low overpotential of 13 mV at 10 mA cm −2 , a small Tafel slope of 22 mV dec −1 , an enhanced intrinsic activity, and a greater durability than commercial Pt black catalyst.
Publisher: Wiley
Date: 20-03-2022
Abstract: Oxygen evolution reaction (OER) is a key half‐reaction in many electrochemical transformations, and efficient electrocatalysts are critical to improve its kinetics which is typically sluggish due to its multielectron‐transfer nature. Perovskite oxides are a popular category of OER catalysts, while their activity remains insufficient under the conventional adsorbate evolution reaction scheme where scaling relations limit activity enhancement. The lattice oxygen‐mediated mechanism (LOM) has been recently reported to overcome such scaling relations and boost the OER catalysis over several doped perovskite catalysts. However, direct evidence supporting the LOM participation is still very little because the doping strategy applied would introduce additional active sites that may mask the real reaction mechanism. Herein, a dopant‐free, cation deficiency manipulation strategy to tailor the bulk diffusion properties of perovskites without affecting their surface properties is reported, providing a perfect platform for studying the contribution of LOM to OER catalysis. Further optimizing the A‐site deficiency achieves a perovskite candidate with excellent intrinsic OER activity, which also demonstrates outstanding performance in rechargeable Zn–air batteries and water electrolyzers. These findings not only corroborate the key role of LOM in OER electrocatalysis, but also provide an effective way for the rational design of better catalyst materials for clean energy technologies.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3EE02695G
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TA02417A
Abstract: An ex situ ultra-fast cation exchange strategy to develop superior OER electrocatalysts with outstanding catalytic performance is developed.
Publisher: Research Square Platform LLC
Date: 24-06-2023
DOI: 10.21203/RS.3.RS-2984162/V1
Abstract: Reversible proton ceramic electrochemical cells (R-PCECs), as solid-state ion devices capable of efficient power generation and energy storage in the medium temperature range, are expected to transform the global pattern of over-dependence on fossil fuels. A major obstacle to their commercial application is the lack of suitable air electrodes that can function effectively and stably in both fuel cell and electrolysis modes. Here, we report a novel triple-conducting (e − /O 2− /H + ) hybrid electrode, composed of a cubic perovskite phase Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ and a hexagonal phase Ba 4 Sr 4 (Co 0.8 Fe 0.2 ) 4 O 16−δ , which may meet the stringent requirements of R-PCECs in terms of activity, conductivity, and durability as an air electrode. Specifically, the corresponding single cell achieves an exciting current density of 3.73 A cm − 2 @ 1.3 V in electrolysis mode and an ultrahigh peak power density of 1.99 W cm − 2 in fuel cell mode at 650°C. Such hybrid electrode can be facilely created through tuning the ratio of A-site to B-site element contents in (Ba 0.5 Sr 0.5 ) x Co 0.8 Fe 0.2 O 2+x−δ precursor. In contrast to the widely applied method of creating self-assembled hybrids by breaking through material tolerance limits, the strategy of adjusting the stoichiometric ratio of the A-site/B-site not only allows for strong interactions and correlations between hybrid phases, but also efficiently modifies the phases content. A synergistic effect between the cubic and hexagonal phases presents in the hybrid electrode, which enhances the oxygen reduction and evolution reaction activity and the protonic conductivity and suppresses the thermal expansion, making it outstanding performance in terms of both oxygen activation and durability.
Publisher: Springer Science and Business Media LLC
Date: 06-07-2020
DOI: 10.1038/S41467-020-17108-5
Abstract: Ion leaching from pure-phase oxygen-evolving electrocatalysts generally exists, leading to the collapse and loss of catalyst crystalline matrix. Here, different from previous design methodologies of pure-phase perovskites, we introduce soluble BaCl 2 and SrCl 2 into perovskites through a self-assembly process aimed at simultaneously tuning dual cation/anion leaching effects and optimizing ion match in perovskites to protect the crystalline matrix. As a proof-of-concept, self-assembled hybrid Ba 0.35 Sr 0.65 Co 0.8 Fe 0.2 O 3- δ (BSCF) nanocomposite (with BaCl 2 and SrCl 2 ) exhibits the low overpotential of 260 mV at 10 mA cm -2 in 0.1 M KOH. Multiple operando spectroscopic techniques reveal that the pre-leaching of soluble compounds lowers the difference of interfacial ion concentrations and thus endows the host phase in hybrid BSCF with abundant time and space to form stable edge/face-sharing surface structures. These self-optimized crystalline structures show stable lattice oxygen active sites and short reaction pathways between Co–Co/Fe metal active sites to trigger favorable adsorption of OH − species.
Publisher: Springer Science and Business Media LLC
Date: 03-2018
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-06-2017
Abstract: A novel strategy to tweak the oxygen evolution activity of nanofilms by exploiting the film-substrate redox interaction.
Publisher: Elsevier BV
Date: 07-2023
Publisher: Elsevier BV
Date: 11-2021
Publisher: Wiley
Date: 25-03-2019
Publisher: SAGE Publications
Date: 07-2021
DOI: 10.1177/26318318211028845
Abstract: Koro syndrome has been colorfully described as a pathological distortion of one’s body image of the genital organ. In Koro, body image dysphoria is characterized by severe anxiety related to the delusional idea that one’s genitals will shrink and retract into one’s abdomen, eventually leading to death. This syndrome was first reported in South East Asia, where endemics have been described, but it has also sporadically occurred globally. We present a systematic literature review on Koro syndrome and report 7 cases from Canada. A search review with PubMed and Google Scholar resulted in 504 entries. Sixty-seven manuscripts were eventually selected following a thorough elimination process. The resultant literature underscored the cultural ersity that underlay the reported cases. Various aspects of Koro have been examined (eg, etiological, clinical, diagnostic, and cultural aspects). It has stimulated substantial scholarly debate, discussions, correspondences, and arguments from anthropological, psychiatric, psychological, and biological perspectives. In our series, it seems that Koro could have been misattributed here. The primary concern was not with penile retraction of the cases. To our knowledge, this is the first time that a series of cases is documented from North America where the syndrome is often ignored. We highlight the potential differences between the classical Koro syndrome and a collection of beliefs related to the perception or delusion of penile retraction in other codable psychiatric disorders, Koro-like syndrome. Understanding Koro syndrome beyond geographic boundaries is in line with our collected case reports of Koro from outside Asia.
Publisher: Elsevier BV
Date: 03-2023
Publisher: American Chemical Society (ACS)
Date: 27-03-2020
Publisher: American Chemical Society (ACS)
Date: 07-11-2022
Abstract: Nanomaterial is the Holy Grail of material science, which has been widely applied in the fields of energy, environment, chemistry, and biomedicine. Its catalytic merits were usually ascribed to the advantages of size effect, strain effect, and covalent effect. Noncovalent interactions are critical in the catalysis processes but often overlooked. Herein, different from the traditional understandings, we discover for the first time and give systematic insights into a unique noncovalent terminal σ-hole phenomenon in the 3
Publisher: Springer Science and Business Media LLC
Date: 11-2017
No related grants have been discovered for Daqin Guan.