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Boosting photocatalytic hydrogen evolution of g-C_(3)N_(4) catalyst via lowering the Fermi level of co-catalyst

Nano Research 2022年第2期15卷 1128-1134页

作者： Hairui Cai Bin Wang Laifei Xiong Jinglei Bi Hanjing Hao Xiaojing Yu Chao Li Jiamei Liu Shengchun Yang MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter Key Laboratory of Shaanxi for Advanced Materials and Mesoscopic PhysicsState Key Laboratory for Mechanical Behavior of MaterialsSchool of PhysicsXian Jiaotong UniversityNo.28 West Xianning RoadXi'an 710049China Shaanxi Collaborative Innovation Center for Hydrogen Fuel Cell Performance Improvement Xian Jiaotong UniversityNo.28 West Xianning RoadXi'an 710049China School of Materials Science and Engineering Xi'an University of TechnologyXi'an 710048China Instrument Analysis Center of Xian Jiaotong University Xian Jiaotong UniversityNo.28 West Xianning RoadXi'an 710049China

The photocatalytic performances are highly dependent on the charge separation and surface reaction kinetics of photocatalysts.Aiming at figuring out the effects of co-catalyst with the lower Fermi level on photocatalytic activity,we tuned the Fermi level of Pt nanoparticles on g-C_(3)N_(4)(GCN)by introducing Co atom.Experimental results show that lowering the Fermi level of co-catalyst does not alter light absorption of GCN due to the invariable structure.Besides,Pt_(3)Co with a lower Fermi level contributes less positive influence on charge separation in GCN due to an opposite effect from the stronger electron-trap ability of Pt_(3)Co and increased band bending in GCN-Pt_(3)Co.The density functional theory(DFT)calculations indicate that GCN-Pt_(3)Co has faster surface reaction kinetics than GCN-Pt,owing to easier dissociation of H_(2)O molecules and faster desorption of H^(*)on Pt_(3)Co.Consequently,GCN-Pt_(3)Co exhibits an excellent H_(2) evolution rate with 2.91 mmol g^(-1)·h^(-1),which 2.67 times that of GCN-Pt.

关键词： Schottky heterojunction surface reactions band bending Fermi level photocatalytic hydrogen evolution

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Deciphering engineering principle of three-phase interface for advanced gas-involved electrochemical reactions

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Journal of Energy Chemistry 2023年第5期80卷 302-323,I0008页

作者： Yanzheng He Sisi Liu Mengfan Wang Qiyang Cheng Tao Qian Chenglin Yan Collaborative Innovation Center of Suzhou Nano Science and Technology College of EnergySoochow UniversitySuzhou 215006JiangsuChina School of Chemistry and Chemical Engineering Nantong UniversityNantong 226019JiangsuChina Light Industry Institute of Electrochemical Power Sources Suzhou 215600JiangsuChina

As an alternative to conventional energy conversion and storage reactions,gas-involved electrochemical reactions,including the carbon dioxide reduction reaction(CO_(2)RR),nitrogen reduction reaction(NRR)and hydrogen evolution reaction(HER),have become an emerging research direction and have gained increasing attention due to their advantages of environmental friendliness and sustainability.Various studies have been designed to accelerate sluggish kinetics but with limited results.Most of them promote the reaction by modulating the intrinsic properties of the catalyst,ignoring the synergistic effect of the reaction as a whole.Due to the introduction of gas,traditional liquid-solid two-phase reactions are no longer applicable to future research.Since gas-involved electrochemical reactions mostly occur at the junctions of gaseous reactants,liquid electrolytes and solid catalysts,the focus of future research on reaction kinetics should gradually shift to three-phase reaction interfaces.In this review,we briefly introduce the formation and constraints of the three-phase interface and propose three criteria to judge its merit,namely,the active site,mass diffusion and electron mass transfer.Subsequently,a series of modulation methods and relevant works are discussed in detail from the three improvement directions of‘exposing more active sites,promoting mass diffusion and accelerating electron transfer’.Definitively,we provide farsighted insights into the understanding and research of three-phase interfaces in the future and point out the possible development direction of future regulatory methods,hoping that this review can broaden the future applications of the three-phase interface,including but not limited to gas-involved electrochemical reactions.

关键词： Three-phase reaction surface reactions Mass diffusion Electron transfer Gas-involved electrochemical reactions

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Carbon spheres with rational designed surface and secondary particle-piled structures for fast and stable sodium storage

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Journal of Energy Chemistry 2021年第3期30卷 368-376页

作者： Wenlong Shao Fangyuan Hu Siyang Liu Tianpeng Zhang Ce Song Zhihuan Weng Jinyan Wang Xigao Jian State Key Laboratory of Fine Chemicals Department of Polymer Materials&EngineeringLiaoning Province Engineering Research Centre of High Performance ResinsDalian University of TechnologyDalian 116024LiaoningChina School of Materials Science and Engineering Key Laboratory of Energy Materials and Devices(Liaoning Province)State Key Laboratory of Fine ChemicalsLiaoning Province Engineering Centre of High Performance ResinsDalian University of TechnologyDalian 116024LiaoningChina School of Mathematical Sciences Dalian University of TechnologyDalian 116024LiaoningChina

The electrochemical performance of hard carbon in sodium storage is still limited by its poor cycling stability and rate capability because of the sluggish kinetics process.In this study,we use a simple and effective method to accelerate the kinetics process by engineering the structure of the electrode to promote its surface and near-surface reactions.This goal is realized by the use of slightly aggregated ultra-small carbon spheres.The large specific surface area formed by the small spheres can provide abundant active sites for electrochemical reactions.The abundant mesopores and macropores derived from the secondary particle piled structure of the carbon spheres could facilitate the transport of electrolytes,shorten the diffusion distance of Na^(+)and accommodate the volume expansion during cycling.Benefiting from these unique structure features,PG700-3(carbon spheres with the diameters of 40-60 nm carbonized at 700℃)exhibits high performance for sodium storage.A high reversible capacity of 163 mAh g^(-1) could be delivered at a current density of 1.0 A g^(-1) after 100 cycles.Interestingly,at a current density of 10.0 A g^(-1),the specific capacity of PG700-3 gradually increases to 140 mAh g^(-1) after 10000 cycles,corresponding to a capacity retention of 112%.Given the enhanced kinetics of SIBs reactions,PG700-3 exhibits an excellent rate capability,i.e.,230 and 138 mAh g^(-1) at 0.1 and 5.0 A g^(-1),respectively.This study provides a facile method to attain high performance anode materials for SIBs.The design strategy and improvement mechanism could be extended to other materials for high rate applications.

关键词： Sodium ion batteries Anode Carbon spheres High rate capability surface reactions

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Chemical Investigation of the NO_x Detection Mechanisms by Semiconductor Metal Oxide Nanoparticles

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稀有金属材料与工程 2006年第A3期35卷 40-42页

作者： Marie-Isabelle Baraton Lhadi Merhari SPCTS-UMR CNRS 6638 Faculty of SciencesF-87060 LimogesFrance CERAMEC R&D F-87000 LimogesFrance

This work reports an FTIR study of the NO_x adsorption/desorption cycles on tin oxide nanosized particles under the operating conditions of real sensors (150℃,in presence of O_2).The chemical reactions are monitored in situ and correlated with the variations of the SnO_2 electrical conductivity.On the basis of the FTIR spectra,two contributing mechanisms for the NO_x detection are suggested.The first one presents the formation of bridged nitrate groups bound to the SnO_2 surface via oxygen vacancies acting as electron donor sites.The second mechanism also involves surface oxygen vacancies in the coordination of NO_x,but this time the formation of NO_x anionic species is considered.Both mechanisms lead to the decrease of the electrical conductivity under NO_x adsorption.However,the bridged nitrate groups are not reversible under gas desorption and thus irreversibly contaminate the surface after the first NO_x adsorption.On the contrary,the nitrosyl anionic species are reversible and,from the second NO_x adsorption/desorption cycle,ensure the reproducibility of the sensor response.

关键词： NO_x detection surface reactions FTIR spectroscopy Tin oxide SnO2 nanoparticles chemical sensors

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surface defect engineering of metal oxides photocatalyst for energy application and water treatment

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Journal of Materiomics 2021年第2期7卷 388-418页

作者： Pankaj Raizada Vatika Soni Abhinandan Kumar Pardeep Singh Aftab Aslam Parwaz Khan Abdullah M.Asiri Vijay Kumar Thakur Van-Huy Nguyen Advance School of Chemical Sciences Shoolini UniversitySolanHP173229India Center of Excellence for Advanced Materials Research King Abdulaziz UniversityP.O.Box 80203Jeddah21589Saudi Arabia Chemistry Department Faculty of ScienceKing Abdulaziz UniversityP.O.Box 80203Jeddah21589Saudi Arabia Biorefining and Advanced Materials Research Centre Scotland Rural College(SRUC)EdinburghUnited Kingdom Institute of Research and Development Duy Tan UniversityDa Nang550000Viet Nam

Despite metal oxides offer excellent characteristics in the field of photocatalysis,they often suffer from charge carrier recombination as well as limited visible response,which indeed reduce the charge kinetics process and ultimately reduce the photocatalytic output.Defect engineering is a sophisticated technique to manufacture defects and alter the geometric structure and chemical environment of the host.The present study provides an all-inclusive outline of recent developments on the classification of metal oxide defects based on the dimensions of a host crystal lattice.Precisely,surface modification of metal oxides through 0D(point),1D(line),2D(planar),and 3D(volume)defects with their subsequent mechanism and impact on photocatalytic performance are presented.By wisely amending the morphology(cores along with the shells)and electronic structure of metal oxide photocatalysts(TiO_(2),ZnO,Bi_(2)O_(3),Fe_(2)O_(4) etc.)through different attuned and veritable approaches,their photocatalytic activity can be substantially improved.Optimal studies on defect engineering not only expose the altered physicochemical features but also modulate the electron-hole pair dynamics,stability,and active radical production for various photoredox reactions.Altered atomic,as well as electronic configuration,facilitated a photocatalyst material to have different optical features,adsorption properties along with improved carrier transfer as well as isolation rate.Thus,the systematic exploration of photocatalytic rudiments of defect rich metal oxide for various applications such as H_(2) evolution,CO_(2) reduction,pollutant degradation,and bacterial disinfection could bring significant research advancement in this field.

关键词： Defect engineering Nanostructured metal oxides Photocatalysis surface reactions Point defects Dislocations Boundaries Voids

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Effect of surface Site on the Spin State for the Interaction of NO with Pd₂, Rh₂ and PdRh Nanoparticles Supported at Regular and Defective MgO(001) surfaces

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Open Journal of Physical Chemistry 2016年第1期6卷 1-20页

作者： S. Abdel Aal Department of Chemistry Faculty of Science Benha University Benha Egypt

An attempt has been made to analyze the effect of surface site on the spin state for the interaction of NO with Pd2, Rh2 and PdRh nanoparticles that supported at regular and defective MgO(001) surfaces. The adsorption properties of NO on homonuclear, Pd2, Rh2, and heteronuclear transition metal dimers, PdRh, that deposited on MgO(001) surface have been studied by means of hybrid density functional theory calculations and embedded cluster model. The most stable NO chemisorption geometry is in a bridge position on Pd2 and a top configuration of Rh2 and PdRh with N-down oriented. NO prefers binding to Rh site when both Rh and Pd atoms co-exist in the PdRh. The natural bond orbital analysis (NBO) reveals that the electronic structure of the adsorbed metal represents a qualitative change with respect to that of the free metal. The adsorption properties of NO have been analyzed with reference to the NBO, charge transfer, band gaps, pairwise and non-pairwise additivity. The binding of NO precursor is dominated by the E(i)Mx-NO pairwise additive components and the role of the support was not restricted to supporting the metal. The adsorbed dimers on the MgO surface lose most of the metal-metal interaction due to the relatively strong bond with the substrate. Spin polarized calculations were performed and the results concern the systems in their more stable spin states. Spin quenching occurs for Rh atom, Pd2, Rh2 and PdRh complexes at the terrace and defective surfaces. The adsorption energies of the low spin states of spin quenched complexes are always greater than those of the high spin states. The metal-support and dimer-support interactions stabilize the low spin states of the adsorbed metals with respect to the isolated metals and dimers. Although the interaction of Pd, Rh, Pd2, Rh2 and PdRh particles with Fs sites is much stronger than the regular sites O2-, the adsorpt

关键词： surface reactions NO Bimetallic Nanoparticles Spin State and Charge Transfer

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