ORCID Profile
0000-0001-9294-1972
Current Organisations
Institute of Acoustics Chinese Academy of Sciences
,
Fudan University
,
Nanyang Technological University
,
East China Normal University
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Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CP00088D
Abstract: The chemistry and physics of under-coordination at a surface, which determines the process of catalytic reactions and growth nucleation, is indeed fascinating. However, extracting quantitative information regarding the coordination-resolved surface relaxation, binding energy, and the energetic behavior of electrons localized in the surface skin from photoelectron emission has long been a great challenge, although the surface-induced core level shifts of materials have been intensively investigated. Here we show that a combination of the theories of tight binding and bond order-length-strength (BOLS) correlation [C. Q. Sun, Prog. Solid State Chem., 2007, 35, 1-159], and X-ray photoelectron spectroscopy (XPS) has enabled us to derive quantitative information, by analyzing the Be 1s energy shift of Be(0001), (1010), and (1120) surfaces, for demonstration, regarding: (i) the 1s energy level of an isolated Be atom (106.416 ± 0.004 eV) and its bulk shift (4.694 eV) (ii) the layer- and orientation-resolved effective atomic coordination (3.5, 3.1, 2.98 for the first layer of the three respective orientations), local bond strain (up to 19%), charge density (133%), quantum trap depth (110%), binding energy density (230%), and atomic cohesive energy (70%) of Be surface skins up to four atomic layers in depth. It is affirmed that the shorter and stronger bonds between under-coordinated atoms perturb the Hamiltonian and hence the fascinating localization and densification of surface electrons. The developed approach can be applied to other low-dimensional systems containing a high fraction of under-coordinated atoms such as adatoms, atomic defects, terrace edges, and nanostructures to gain quantitative information and deeper insight into their properties and processes due to the effect of coordination imperfection.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9EN00017H
Abstract: Our mesoporous carbon single crystals exhibit an extraordinary capacitive deionization performance.
Publisher: Elsevier BV
Date: 07-2009
Publisher: World Scientific Pub Co Pte Lt
Date: 08-2006
DOI: 10.1142/S0219581X0600453X
Abstract: A method of impedance frequency response analysis (FRA) with template multilayer organic capacitor was studied to evaluate printable materials for all-printed organic field-effect transistors (OFETs). The new method allows us not only to characterize simultaneously dielectric and conductive behaviors of the materials but also to distinguish contributions to electrical conduction or to polarization from different sources such as dielectric layer, semiconductor layer, and different interfaces for OFETs. As a dielectric layer for OFETs, Urathan is preferred because of lower conductivity, nonmetallic conduction behavior at high temperature, and lower interfacial resistance. Conductivity and dielectric enhancement of Urathan can be realized by heating. The critical temperature for conductivity and dielectricity transition was calculated from FRA from temperature dependent experiments. The method could be a standard for fast screening and assessing printable materials for OFETs.
Publisher: American Chemical Society (ACS)
Date: 09-12-2009
DOI: 10.1021/JP908220A
Publisher: World Scientific Pub Co Pte Lt
Date: 04-2009
DOI: 10.1142/S0218625X09012573
Abstract: Cu , Al , and Ti films of ~ 10 nm thickness were deposited on porous silicon (PS) at room temperature using Filtered Cathodic Vacuum Arc system and annealed at 800°C for 10 min in vacuum. The PS layers were obtained by anodization of Si wafer. X-ray photoelectron spectroscopy, photoluminescence (PL), photo-absorption (PA), and X-ray diffraction studies revealed that before annealing just Cu -deposited s le exhibited PL blueshift, PA redshift, and Si -2p level shift due to the Cu diffusion at the surface of PS. While after annealing, Cu - and Ti -deposited s les exhibited obvious PA redshift and Si -2p level shift, which arise from the crystal field variation due to the formation of Cu / Ti silicides at the surface as well as the conduction electronic transportation.
Publisher: Elsevier BV
Date: 06-2021
Publisher: AIP Publishing
Date: 15-08-2011
DOI: 10.1063/1.3626044
Abstract: Correlation between the elastic modulus (B) and the Raman shift (Δω) of TiO2 and their responses to the variation of crystal size, applied pressure, and measuring temperature have been established as a function depending on the order, length, and energy of a representative bond for the entire specimen. In addition to the derived fundamental information of the atomic cohesive energy, binding energy density, Debye temperature and nonlinear compressibility, theoretical reproduction of the observations clarified that (i) the size effect arises from the under-coordination induced cohesive energy loss and the energy density gain in the surface up to skin depth (ii) the thermally softened B and Δω results from bond expansion and bond weakening due to vibration and, (iii) the mechanically stiffened B and Δω results from bond compression and bond strengthening due to mechanical work hardening. With the developed premise, one can predict the changing trends of the concerned properties with derivatives of quantitative information as such from any single measurement alone.
Publisher: Elsevier BV
Date: 09-2003
Publisher: IOP Publishing
Date: 16-11-2004
Publisher: Elsevier BV
Date: 08-2015
Publisher: Elsevier BV
Date: 02-2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CY00013C
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9MH00306A
Abstract: Metal–organic framework olypyrrole hybrids are synthesized and directly used in capacitive deionization for the first time.
Publisher: Elsevier BV
Date: 02-2011
Publisher: Elsevier BV
Date: 11-2012
Publisher: Elsevier BV
Date: 06-2018
Publisher: AIP Publishing
Date: 26-07-2004
DOI: 10.1063/1.1766086
Abstract: CF 4 plasma-passivation enhanced size dependence of the blueshift in photoemission and photoabsorption, E2p-level shift, and band-gap expansion of porous silicon has been measured and analyzed numerically based on the recent “bond order-length-strength” correlation [C. Q. Sun, Phys. Rev. B 69, 045105 (2004)]. Matching predictions to the measurements conducted before and after fluorination reveals that fluorination further enhances both the crystal binding intensity that determines the band gap and core level shift and the electron-phonon coupling that contributes to the energies of photoemission and photoabsorption. This approach enables us to discriminate the effect of surface-bond contraction from the effect of surface-bond nature alteration on the unusual behavior of photons, phonons, and electrons in nanosolid Si.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3TA10981J
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CY00109D
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CY00622H
Abstract: Light-conversion phosphor-based composites including up-conversion, down-conversion, and long afterglow phosphor-semiconductors for efficient photocatalysis are summarized.
Publisher: Elsevier BV
Date: 06-2009
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TA02524A
Publisher: Elsevier BV
Date: 07-2016
Publisher: IOP Publishing
Date: 05-12-2001
Publisher: American Chemical Society (ACS)
Date: 19-02-2004
DOI: 10.1021/JP037891S
Publisher: American Chemical Society (ACS)
Date: 24-08-2009
DOI: 10.1021/JP905336J
Publisher: Elsevier BV
Date: 08-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CC14875C
Abstract: CdS-reduced graphene oxide (RGO) composites are successfully synthesized via the microwave-assisted reduction of graphite oxide in a CdS precursor solution using a microwave synthesis system. The photocatalytic performances of CdS-RGO composites in the reduction of Cr(VI) are investigated. The results show that CdS-RGO composites exhibit enhanced photocatalytic performance for the reduction of Cr(VI) with a maximum removal rate of 92% under visible light irradiation as compared with pure CdS (79%) due to the increased light absorption intensity and the reduction of electron-hole pair recombination in CdS with the introduction of RGO.
Publisher: Springer Science and Business Media LLC
Date: 15-03-2011
DOI: 10.1557/JMR.2011.22
Publisher: AIP Publishing
Date: 29-07-2003
DOI: 10.1063/1.1594821
Abstract: Dielectric impedance measurements of porous silicon within the frequency range of 50 Hz–1.0 MHz and temperature range of 298–798 K revealed three semicircles in a Cole–Cole plot when the temperature is raised to 773 K they are thought to correspond to contributions from the grain interior, grain boundary, and electrode/film interface, respectively. The enhancement in conductivity by heating follows an Arrhenius law with an activation energy transition from 0.07 to 0.79 eV at ∼565 K, which originates from band tail hopping that occurs around the Fermi edge. At a critical temperature, a high degree of dispersion in the real and imaginary parts of the permittivity also occurs at low frequencies. This dispersion behavior is interpreted as a combination of electron-lattice polarization associated to the band tail hopping and the crystal field weakening due to thermal expansion.
Publisher: Elsevier BV
Date: 04-2018
Publisher: American Physical Society (APS)
Date: 04-10-2005
Publisher: American Chemical Society (ACS)
Date: 08-05-2003
DOI: 10.1021/JP0272015
Publisher: American Chemical Society (ACS)
Date: 23-10-2002
DOI: 10.1021/JP0266805
Publisher: Elsevier BV
Date: 2006
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9MH01829H
Abstract: This work reports the layer-by-layer motif synthesis of 3D interconnected nitrogen–iron-doped carbon tubes (3D-FeNC tubes) by using continuous polymeric fibers as templates with high capacitive deionization performance in oxygenated saline water.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1RA00298H
Publisher: Elsevier BV
Date: 02-2005
Publisher: American Scientific Publishers
Date: 05-2014
Publisher: Trans Tech Publications, Ltd.
Date: 07-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.444.17
Abstract: Shrinking the size of a solid down to nanometer scale is indeed fascinating, which makes all the otherwise constant physical quantities to be tunable such as the Young’s modulus, dielectric constant, melting point, etc. The variation of size also generates novel properties that can hardly be seen in the bulk such as the conductor-insulator and nonmagnetic-magnetic transition of noble metals at the nanoscale. Although the physics of materials at the nanoscale has been extensively investigated, the laws governing the energetic and dynamic behavior of electrons at such a scale and their consequences on the tunable physical properties of nanostructures have not been well understood [C. Q. Sun, Prog Solid State Chem 35, 1-159 (2007) Prog Mater Sci 54, 179-307 (2009)]. The objective of the contribution is to update the recent progress in dealing with the coordination-resolved energetic and dynamic behavior of bonds in the low-dimensional systems with consideration of the joint effect of temperature and pressure. It is shown that the broken-bond-induced local strain and the associated charge and energy quantum trapping at the defect sites perturbs the atomic cohesive energy, electroaffinity, the Hamiltonian and the associated properties of entities ranging from point defects, surfaces, nanocavities and nanostructures. Application of the theories to observations has led to consistent understanding of the behavior of nanometer-sized materials and the interdependence of these entities as well as the means of determining the bond energy through the temperature-dependent measurements.
Publisher: American Chemical Society (ACS)
Date: 18-08-2007
DOI: 10.1021/JP0727087
Publisher: American Vacuum Society
Date: 03-2004
DOI: 10.1116/1.1651108
Abstract: The effect of plasma fluorination on the band gap, 2p core-level energy, and the dielectric behavior of porous silicon (PS) prepared under constant conditions has been examined using Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, photoluminescence, and reflection. It has been found that with increasing extent of fluorination, the band gap expands, and the 2p level and the dielectric constant drop down substantially compared with those of the as-grown PS, being quite similar to the effect of particle size reduction. These findings could be interpreted as the fluorination-induced crystal field enhancement and the valence charge repopulation of silicon. The surface fluorination may provide an effective method for tuning the optical and dielectric properties of nanometric silicon.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B917326A
Abstract: Incorporating the BOLS correlation algorithm [Y. Sun, J. Phys. Chem. C, 2009, 113, 14696] into high-resolution XPS measurements [J. N. Andersen, et al., Phys. Rev. B: Condens. Matter, 1994, 50, 17525 A. Baraldi, et al., New J. Phys., 2007, 9, 143] has produced an effective way of determining the 3d(5/2) energy levels of isolated Rh(302.163 +/- 0.003 eV) and Pd (330.261 +/- 0.004 eV eV) atoms and their respective bulk shifts (4.367 and 4.359 eV) with a refinement of the effective atomic coordination numbers of the top (100), (110), and (111) atomic layers (4.00, 3.87, and 4.26, respectively). It is further confirmed that the shorter and stronger bonds between under-coordinated atoms induce local strain and skin-depth charge-and-energy quantum trapping and, hence, dictate globally the positive core level binding energy shifts.
Publisher: Elsevier BV
Date: 2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CC05673G
Abstract: Here, ultrathin nitrogen-doped carbon/graphene nano-sandwiches were synthesized by carbonization of graphene oxide-based nanosheets, which were fully covered with ultrasmall ZIF-8 nanocrystals.
Publisher: Elsevier BV
Date: 2010
Publisher: Desalination Publications
Date: 2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2RA01107G
Publisher: World Scientific Pub Co Pte Ltd
Date: 08-2005
DOI: 10.1142/S0219581X05003668
Abstract: A new characterization method based on impedance frequency response analysis at different temperatures has been developed to assess and identify the dielectric and semiconductor materials for organic field-effect transistors (OFET). This method can not only characterize simultaneously dielectric and conductive behaviors of materials but also distinguish in idual contributions to electrical conduction or to polarization from layers such as dielectric layer, semiconductor layer, and interfaces in OFET. Two kinds of materials, Urathan and DuPont 5018A as dielectric materials have been used to make a multilayer organic capacitor. It has been observed that Urathan, due to its lower conductivity, non-metallic conduction behavior at high temperature, and lower interfacial resistance, is more suitable as dielectric layer for OFET. Urathan appears an enhancement in conductivity by heating following an Arrhenius law with an activation energy transition from 0.002 to 0.24 eV at ~307 K, which originates from band tail hopping that occurs around the Fermi edge. At ~314 K, a dielectric transition also occurs, which is interpreted as a combination of electron polarization associated to the band tail hopping. The materials were used to fabricate OEFT, which performance was in agreement with that obtained from impedance analysis of the organic capacitor.
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 04-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B922677J
Abstract: The ability of a catalyst to accept or donate charge is the key to the process of catalytic reaction. However, the determination of the catalytic nature of a specimen as yet remains a great challenge. Here we report an effective yet simple method for this purpose based on the tight binding theory considerations and XPS monitoring of the evolution of valence and core electrons upon alloy formation. Firstly, we measured the valence and core band charge density of the constituent elements of Cu, Ag, and Pd and then the respective states upon alloy formation. A subtraction of the resultant spectrum of the alloy by the composed elemental spectra gives the residual that shows clearly the occurrence of charge trapping or polarization. We found that the valence and the core electrons of the CuPd alloy shift positively to deeper energies, opposite to the occurrences in the AgPd alloy. Findings clarify for the first time that CuPd serves as an acceptor due to quantum trapping and the AgPd as a donor because of charge polarization, which also explain why AgPd and CuPd perform very differently as important catalysts.
Publisher: AIP Publishing
Date: 15-10-2007
DOI: 10.1063/1.2798941
Abstract: The thermally induced softening of the elastic and vibronic identities in crystals and their correlations have long been a puzzle. Analytical solutions have been developed, showing that the detectable elastic and vibronic properties could be related directly to the bonding parameters, such as bond length and strength, and their response to the temperature change. Reproduction of measured T-dependent Young’s modulus and Raman shift of Si, Ge, and diamond reveals that the thermally driven softening of the elasticity and the optical Raman frequency arises from bond expansion and vibration, with derived information about the atomic cohesive energy and clarification of their interdependence.
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.JCIS.2013.07.045
Abstract: Bi2O3-reduced graphene oxide (RGO) composites were successfully synthesized via microwave-assisted reduction of graphite oxide in Bi2O3 precursor solution using a microwave system. Their morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) and methyl orange (MO) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, UV-vis absorption spectroscopy, and electrochemical impedance spectroscopy, respectively. The results show that the RGO addition can enhance the photocatalytic performance of Bi2O3-RGO composites. Bi2O3-RGO composite with 2 wt.% RGO achieves maximum MO and MB degradation rates of 93% and 96% at 240min under visible light irradiation, respectively, much higher than those for the pure Bi2O3 (78% and 76%). The enhanced photocatalytic performance is ascribed to the increased light adsorption and the reduction in electron-hole pair recombination in Bi2O3 with the introduction of RGO.
Publisher: American Chemical Society (ACS)
Date: 19-07-2021
Abstract: Alternative water resources (seawater, brackish water, atmospheric water, sewage,
Publisher: The Chemical Society of Japan
Date: 15-08-2020
Publisher: World Scientific Pub Co Pte Lt
Date: 10-2011
DOI: 10.1142/S2010135X11000549
Abstract: Correlation between the elastic and the vibronic behavior of TiO 2 and their responses to the variation of crystal size, applied pressure, and measuring temperature has been investigated based on the bond order–length-strength correlation mechanism. Theoretical reproduction of the measurements clarified that: (i) the elastic modulus (B) and the Raman shifts (Δω) are strongly correlated and we can know either one of the B or the Δω from the other (ii) the under-coordination induced cohesive energy loss and the energy density gain in the surface up to skin depth determines the size effect (iii) bond expansion and bond weakening due to thermal vibration originates the thermally softened elastic modulus and the Raman shifts and (iv) bond compression and bond strengthening results in the mechanically stiffened elastic modulus and the Raman shifts. With the developed premise, one can predict the changing trends of the concerned properties with derivatives of quantitative information of the atomic cohesive energy, binding energy density, Debye temperature, and nonlinear compressibility of the specimen.
Publisher: American Chemical Society (ACS)
Date: 09-10-2009
DOI: 10.1021/JP907726B
Publisher: Elsevier BV
Date: 08-2005
Publisher: Wiley
Date: 11-04-2007
DOI: 10.1002/JRS.1683
Publisher: AIP Publishing
Date: 02-2011
DOI: 10.1063/1.3544042
Abstract: Although the physics behind the bulk modulus, B(T,P), as a function of temperature (T) and pressure (P), has been intensively investigated, an atomic scale understanding of this attribute remains a high challenge. Here, we show that the B(T,P) for BaXO3 (X=Ti,Zr,Nb) can be established by connecting the B directly to the bond length and bond energy and their response to the applied T and P in the form of binding energy density, B[E/d3(T,P)]. Besides an estimation of the Debye temperature and single bond energy, outcomes clarified that the thermally softened B arises from bond expansion and bond weakening due to lattice vibration and the mechanically stiffened B results from bond compression and bond strengthening due to mechanical work hardening.
Publisher: IEEE
Date: 2006
Publisher: Elsevier BV
Date: 03-2021
Publisher: American Chemical Society (ACS)
Date: 09-09-2021
Publisher: Jenny Stanford Publishing
Date: 30-03-2016
DOI: 10.1201/B19904-11
Publisher: American Chemical Society (ACS)
Date: 30-10-2017
Abstract: Metal-organic frameworks (MOFs) with high porosity and a regular porous structure have emerged as a promising electrode material for supercapacitors, but their poor electrical conductivity limits their utilization efficiency and capacitive performance. To increase the overall electrical conductivity as well as the efficiency of MOF particles, three-dimensional networked MOFs are developed via using preprepared conductive polypyrrole (PPy) tubes as the support for in situ growth of MOF particles. As a result, the highly conductive PPy tubes that run through the MOF particles not only increase the electron transfer between MOF particles and maintain the high effective porosity of the MOFs but also endow the MOFs with flexibility. Promoted by such elaborately designed MOF-PPy networks, the specific capacitance of MOF particles has been increased from 99.2 F g
Publisher: Elsevier BV
Date: 11-2013
Publisher: Elsevier BV
Date: 2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CY00452F
Publisher: Elsevier BV
Date: 06-2020
No related grants have been discovered for Likun Pan.