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Journal of Energy Chemistry 2023年第1期76卷 226-232,I0006页

作者： Chengrong Wu Yan Sun Xiaojian Wen Jia-Ye zhang liang Qiao Jun Cheng Kelvin H.L.Zhang State Key laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina School of Physics University of Electronic Science and Technology of ChinaChengdu 610054SichuanChina

Developing highly-active,earth-abundant non-precious-metal catalysts for hydrogen evolution reaction(hER)in alkaline solution would be beneficial to sustainable energy storage.Perovskite oxides are generally regarded as low-active hER catalysts,due to their inapposite hydrogen adsorption and water dissociation.here,we report a detailed study on perovskite laCoO_(3)epitaxial thin films as a model catalyst to significantly enhance the hER performance via an electrochemical activation process.As a result,the overpotential for the activation films to achieve a current density of 0.36 m A/cm^(2)is 238 m V,reduced by more than 200 m V in comparison with that of original samples.Structural characterization revealed the activation process dramatically increases the concentration of oxygen vacancies(Vo)on the surface of laCoO_(3).We established the relationship between the electronic structure induced by Vo and the enhanced hER activity.Further theoretical calculations revealed that the Vo optimizes the hydrogen adsorption and dissociation of water on the surface of laCoO_(3)thin films,thus improving the hER catalytic activity.This work may promote a deepened understanding of perovskite oxides for hER mechanism by Vo adjusting and a new avenue for designing highly active electrochemical catalysts in alkaline solution.

关键词： hydrogen evolution reaction Perovskite oxides Activation process Oxygen vacancies

Transparent conductive SnO_(2)thin films via resonant Ta doping

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Science China Materials 2023年第1期66卷 264-271页

作者： Vedaste Uwihoreye Zhenni Yang Jia-Ye zhang Yu-Mei lin Xuan liang lu Yang Kelvin H.L.Zhang College of Chemistry and Chemical Engineering Xiamen UniversityXiamen 361005China

Transparent conductive oxide(TCO)thin films are highly desired as electrodes for modern flat-panel displays and solar cells.Alternative indium-free TCO materials are highly needed,because of the scarcity and the high price of indium.Based on the mechanism of resonant doping,Ta has been identified as an effective dopant for SnO_(2)to achieve highly conductive and transparent TCO.In this work,we fabricated a series of Ta-doped SnO_(2)thin films(Sn_(1-x)Ta_(x)O_(2),x=0.001,0.01,0.02,0.03)with high conductivity and high optical transparency via a low-cost sol-gel spin coating method.The Sn_(0.98)Ta_(0.02)O_(2)film achieves the highest electrical conductivity of 855 S cm-1with a carrier concentration of2.3×10^(20)cm^(-3)and high mobility of 23 cm^(2)V^(-1)s^(-1).The films exhibit a very high optical transparency of 89.5%in the visible light region.high-resolution X-ray photoemission spectroscopy and optical spectroscopy were combined to gain insights into the electronic structure of the Sn_(1-x)Ta_(x)O_(2)films.The optical bandgaps of the films are increased from 3.96 eV for the undoped SnO_(2)to 4.24 eV for the Sn_(0.98)Ta_(0.02)O_(2)film due to the occupation of the bottom of conduction band by free electrons,i.e.,the Burstein-Moss effect.Interestingly,a bandgap shrinkage is also directly observed due to the bandgap renormalization arising from many-body interactions.The double guarantee of transparency and conductivity in Sn_(1-x)Ta_(x)O_(2)films and the low-cost growth method provide a new platform for optoelectronic and solar cell applications.

关键词： transparent conductive oxide sol-gel spin coating Ta-doped SnO_(2) electronic structure

Solid solution strengthening of high-entropy alloys from first-principles study

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Journal of Materials Science & Technology 2022年第26期121卷 105-116页

作者： H.L.Zhang D.D.Cai X.Sun h.huang S.lu Y.Z.Wang Q.M.hu l.Vitos X.D.Ding State Key laboratory for Mechanical Behavior of Materials Frontier Institute of Science and TechnologyXi’an Jiaotong UniversityXi’an 710049China Key laboratory of Shaanxi Province for Craniofacial Precision Medicine Research College of StomatologyXi’an Jiaotong UniversityXi’an 710049China Department of Materials Science and Engineering The Ohio State University2041 College RoadColumbusOH 43210United States Institute of Metal Research Chinese Academy of SciencesShenyang 110016China Science and Technology on Surface Physics and Chemistry laboratory Jiangyou 621908China Applied Materials Physics Department of Materials Science and EngineeringRoyal Institute of TechnologyStockholm SE-10044Sweden

Solid solution strengthening(SSS)is one kind of strengthening mechanisms and plays an important role in alloy design,in particular for single-phase alloys including high-entropy alloys(hEAs).The classical labusch–Nabarro model and its expansions are most widely applicable to treating SSS of solid solution alloys including both conventional alloys(CAs)and hEAs.In this study,the SSS effects in a series of Febased CAs and hEAs are investigated by using the classical labusch–Nabarro model and its expansions.The size misfit and shear modulus misfit parameters are derived from first-principles calculations.Based on available experimental data in combination with empirical SSS model,we propose fitting constants(i.e.,the ratio between experimental hardness and predicted SSS effect)for these two families of alloys.The predicted host/alloy family-dependent fitting constants can be used to estimate the hardness of these SSS alloys.General agreement between predicted and measured hardness values is satisfactory for both CAs and hEAs,implying that the proposed approach is reliable and successful.

关键词： Alloys Solid solution strengthening hardness Size misfit parameter Shear modulus misfit parameter First-principles calculations

Transparent conductive SnOthin films via resonant Ta doping

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Science China Materials 2022年

作者： Vedaste Uwihoreye Zhenni Yang Jia-Ye zhang Yu-Mei lin Xuan liang lu Yang Kelvin H.L.Zhang College of Chemistry and Chemical Engineering Xiamen University

Transparent conductive oxide(TCO) thin films are highly desired as electrodes for modern flat-panel displays and solar cells. Alternative indium-free TCO materials are highly needed, because of the scarcity and the high price of indium. Based on the mechanism of resonant doping, Ta has been identified as an effective dopant for SnOto achieve highly conductive and transparent TCO. In this work, we fabricated a series of Ta-doped SnOthin films(SnTaO, x= 0.001, 0.01, 0.02, 0.03) with high conductivity and high optical transparency via a low-cost sol-gel spin coating method. The SnTaOfilm achieves the highest electrical conductivity of 855 S cmwith a carrier concentration of 2.3 × 1020 cmand high mobility of 23 cm~2 Vs. The films exhibit a very high optical transparency of 89.5% in the visible light region. high-resolution X-ray photoemission spectroscopy and optical spectroscopy were combined to gain insights into the electronic structure of the SnTaOfilms. The optical bandgaps of the films are increased from 3.96 eV for the undoped SnOto 4.24 eV for the SnTaOfilm due to the occupation of the bottom of conduction band by free electrons, i.e., the Burstein-Moss effect. Interestingly, a bandgap shrinkage is also directly observed due to the bandgap renormalization arising from many-body interactions. The double guarantee of transparency and conductivity in SnTaOfilms and the low-cost growth method provide a new platform for optoelectronic and solar cell applications.

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Enhanced mechanical performance of grain boundary precipitation-hardened high-entropy alloys via a phase transformation at grain boundaries

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Journal of Materials Science & Technology 2021年第27期86卷 271-284页

作者： Y.l.Qi l.Zhao X.Sun h.X.Zong X.D.Ding F.Jiang H.L.Zhang Y.K.Wu l.he F.liu S.B.Jin G.Sha J.Sun State Key laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049China Analytical&Testing Center Northwestern Polytechnical UniversityXi’an710072China School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing210094China

Grain-boundary(GB)precipitation has a significant adverse effect on plasticity of alloys,which easily leads to catastrophic intergranular failure in safety-critical applications under high external loading.herein,we report a novel strategy that uses the local stress concentration induced by GB precipitates as a driving force to trigger phase transformation of preset non-equiatomic high-entropy solid-solution phase at GBs.This in situ deformation-induced phase transformation at GBs introduces a well-known effect:transformation-induced plasticity(TRIP),which enables an exceptional elongation to fracture(above 38%)at a high strength(above 1.5 GPa)in a GB precipitation-hardened high-entropy alloy(hEA).The present strategy in terms of"local stress concentration-induced phase transformations at GBs"may provide a fundamental approach by taking advantage of(rather than avoiding)the GB precipitation to gain a superior combination of high strength and high ductility in hEAs.

关键词： Non-equiatomic Grain-boundary precipitation high-entropy alloys Ductility Transformation-induced plasticity

Direct Z-scheme WO_(3-x) nanowire-bridged TiO_(2) nanorod arrays for highly efficient photoelectrochemical overall water splitting

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Journal of Energy Chemistry 2021年第8期30卷 721-729,I0015页

作者： Sheng lin he Ren Zhi Wu lan Sun Xia-Guang zhang Yu-Mei lin Kelvin H.L.Zhang Chang-Jian lin Zhong-Qun Tian Jian-Feng li State Key laboratory of Physical Chemistry of Solid Surfaces Department of ChemistryCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Shenzhen Research Institute of Xiamen University Shenzhen 518000China Key laboratory of Green Chemical Media and Reactions Ministry of EducationCollaborative Innovation Center of Henan Province for Green Manufacturing of Fine ChemicalsSchool of Chemistry and Chemical EngineeringHenan Normal UniversityXinxiang 453007China

All-solid-state Z-scheme photocatalysts for overall water splitting to evolve h_(2) is a promising strategy for efficient conversion of solar energy.however,most of these strategies require redox mediators.herein,a direct Z-scheme photoelectrocatalytic electrode based on a WO_(3-x)nanowire-bridged TiO_(2)nanorod array heterojunction is constructed for overall water splitting,producing h_(2).The as-prepared WO_(3-x)/TiO_(2)nanorod array heterojunction shows photoelectrochemical(PEC)overall water splitting activity evolving both h_(2) and O_(2)under UV-vis light irradiation.An optimum PEC activity was achieved over a 1.67-WO_(3-x)/TiO_(2)photoelectrode yielding maximum h_(2) and O_(2)evolution rates roughly 11 times higher than that of pure TiO_(2)nanorods without any sacrificial agent or redox mediator.The role of oxygen vacancy in WO_(3-x)in affecting the h_(2) production rate was also comprehensively studied.The superior PEC activity of the WO_(3-x)/TiO_(2)electrode for overall water splitting can be ascribed to an efficient Z-scheme charge transfer pathway between the WO_(3-x)nanowires and TiO_(2)nanorods,the presence of oxygen vacancies in WO_(3-x),and a bias potential applied on the photoelectrode,resulting in effective spatial charge separation.This study provides a novel strategy for developing highly efficient PECs for overall water splitting.

关键词： TiO_(2) nanorod arrays WO_(3-x) nanowire heterostructure Photoelectrochemical hydrogen production

Revealing the correlation between structure evolution and electrochemical performance of high-voltage lithium cobalt oxide

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Journal of Energy Chemistry 2021年第3期30卷 786-794页

作者： Jiajia Wan Jianping Zhu Yuxuan Xiang Guiming Zhong Xiangsi liu Yixiao li Kelvin H.L.Zhang Chaoyu hong Jianming Zheng Kai Wang Yong Yang Collaborative Innovation Center of Chemistry for Energy Materials State Key Laboratory for Physical Chemistry of Solid SurfaceCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina Xiamen Institute of Rare Earth Materials Haixi InstitutesChinese Academy of SciencesXiamen 361021FujianChina Department of Chemical and Biochemical Engineering College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina Ningde Amperex Technology ltd Ningde 352100FujianChina School of Energy Xiamen UniversityXiamen 361005FujianChina

lithium cobalt oxide(lCO)is the dominating cathode materials for lithium-ion batteries(lIBs)deployed in consumer electronic devices for its superior volumetric energy density and electrochemical performances.The constantly increasing demands of higher energy density urge to develop high-voltage lCO via a variety of strategies.however,the corresponding modification mechanism,especially the influence of the long-and short-range structural transitions at high-voltage on electrochemical performance,is still not well understood and needs further exploration.Based on ss-NMR,in-situ X-ray diffraction,and electrochemical performance results,it is revealed that the h3 to h1-3 phase transition dictates the structural reversibility and stability of lCO,thereby determining the electrochemical performance.The introduction of la and Al ions could postpone the appearance of h1-3 phase and induce various types of local environments to alleviate the volume variation at the atomic level,leading to better reversibility of the h1-3 phase and smaller lattice strain,and significantly improved cycle performance.Such a comprehensive long-range,local,and electronic structure characterization enables an in-depth understanding of the structural evolution of lCO,providing a guiding principle for developing high-voltage lCO for high energy density lIBs.

关键词： lithium cobalt oxide high-voltage In-situ XRD Solid-state NMR Structure change

Vertically aligned Ni/NiO nanocomposites with abundant oxygen deficient hetero-interfaces for enhanced overall water splitting

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Science China Chemistry 2022年第10期65卷 1885-1894页

作者： hongxia Wang Meiyan Cui Gaoliang Fu Jiaye zhang Xingyu Ding Irene Azaceta Matthew Bugnet Demie M.Kepaptsoglou Vlado K.lazarov Victor Ade la Peña O’Shea Freddy E.Oropeza Kelvin H.L.Zhang State Key laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China State Key laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China henan Provincial Key laboratory of Nanocomposites and Applications Institute of Nanostructured Functional MaterialsHuanghe Science and Technology CollegeZhengzhou 450006China Department of Physics University of YorkHeslingtonYorkYO105DDUK SuperSTEM laboratory SciTech Daresbury CampusDaresbury WA44ADUK School of Chemical and Process Engineering Univeristy of LeedsLeeds LS29JTUK Univ lyon CNRSINSA LyonUCBLMATEISUMR 551069621 VilleurbanneFrance Photoactivated Processes Unit IMDEA Energy InstituteParque Tecnológico de MóstolesAvda.Ramón de la Sagra 328935 MóstolesMadridSpain

The design of heterostructured transition metal-based electrocatalysts with controlled composition and interfaces is key to increasing the efficiency of the water electrolysis and the elucidation of reaction mechanisms.In this work,we report the synthesis of well-controlled vertically aligned Ni/NiO nanocomposites consisting of Ni nanoclusters embedded in NiO,which result in highly efficient electrocatalysts for overall water splitting.We show that such a high catalytic efficiency toward both the hydrogen evolution reaction(hER)and the oxygen evolution reaction(OER)originates from a synergetic effect at Ni/NiO interfaces that significantly reduces the energy barrier for water dissociation,and favours the formation of reactive h*intermediates on the Ni side of the interface,and Oh_(ads) on the NiO side of the interface.A study of water chemisorption based on near-ambient pressure photoelectron spectroscopy indicates that the abundant hetero-interfaces in Ni/NiO nanocomposite promote the dissociation of water with a three-fold increase in the surface concentration of Oh_(ads) compared with pure NiO.Density functional theory calculations indicate that Ni/NiO interface leads to the reduction of the water dissociation energy barrier due to a high concentration of oxygen vacancies at NiO side of the interface,whereas the formation of highly active metallic Ni sites with an optimal value of Gibbs free energy of h*(ΔG_(h*)=−0.16 eV)owes to a favourable adjustment of the electron energetics at the interface,thus accelerating the overall electrochemical water splitting.

关键词： water splitting hydrogen evolution reaction electronic structure heterostructure vertically aligned nanocomposites

Correlating the electronic structure of perovskite la_(1-x)SrxCoO_(3) with activity for the oxygen evolution reaction:The critical role of Co 3d hole state

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Journal of Energy Chemistry 2022年第2期31卷 637-645页

作者： Zechao Shen Mei Qu Jueli Shi Freddy E.Oropeza Victor A.de la Peña O’Shea Giulio Gorni C.M.Tian Jan P.hofmann Jun Cheng Jun li Kelvin H.L.Zhang State Key laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina Photoactivated Processes Unit IMDEA Energy InstituteParque Tecnológico de MóstolesAvda.Ramón de la Sagra 328935 MóstolesMadridSpain CEllS-AlBA Synchrotron Carrer de la Llum 2-2608290 Cerdanyola del VallèsSpain Surface Science laboratory Department of Materials and Earth SciencesTechnical University of Darmstadt Otto-Berndt-Strasse 364287 DarmstadtGermany

Perovskite laCoO_(3) is being increasingly explored as an effective low-cost electrocatalyst for the oxygen evolution reaction(OER).Sr doping in laCoO_(3)(la1-xSrxCoO_(3))has been found to substantially increase its catalytic activity.In this work,we report a detailed study on the evolution of the electronic structure of la1-xSrxCoO_(3) with 0≤x≤1 and its correlation with electrocatalytic activity for the OER.A combination of X-ray photoemission spectroscopy(XPS)and X-ray absorption spectroscopy(XAS)was used to unravel the electronic density of states(DOS)near the Fermi level(EF),which provide insights into the key electronic structure features for the enhanced OER catalytic activity.Detailed analysis on the Co l-edge XAS suggest that laCoO_(3) has a low spin state with t_(2g)^(6) e_(g)^(0) configuration at room temperature.This implies that the high OER catalytic activity of laCoO_(3) should not be rationalized by the occupancy of eg=1 descriptor.Substituting Sr^(2+) for la^(3+) in laCoO_(3) induces Co4+oxidation states and effectively dopes hole states into the top of valence band.A semiconductor-to-metal transition is observed for x>0.2,due to the holeinduced electronic DOS at the EF and increased hybridization between Co 3 d and O 2 p.Such an electronic modulation enhances the surface adsorption of the*Oh intermediate and reduces the energy barrier for interfacial charge transfer,thus improving the OER catalytic activity in la_(1-x)Sr_(x)CoO_(3).In addition,we found that the la_(1-x)Sr_(x)CoO_(3) surface undergoes amorphization after certain period of OER measurement,leading to a partial deactivation of the electrocatalyst.high Sr doping levels accelerated the amorphization process.

关键词： Perovskite oxide Oxygen evolution Cobalt Electronic structure

Modulation of the electronic states of perovskite SrCrO3 thin films through protonation via low-energy hydrogen plasma implantation approaches

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Frontiers of physics 2020年第1期15卷 43-50页

作者： Meng Wu Shanquan Chen Chuanwei huang Xing Ye haiping Zhou Xiaochun huang Kelvin H.L.Zhang Wensheng Yan lihua zhang Kisslinger Kim Yingge Du Scott Chambers Jin-Cheng Zheng hui-Qiong Wang Fujian Provincial Key laboratory of Semiconductors and Applications Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient DevicesDepartment of PhysicsXiamen UniversityXiamen 361005China Shenzhen Key laboratory of Special Functional Materials College of Materials Science and EngineeringShenzhen UniversityShenzhen 518060China School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 611731China State Key laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China National Synchrotron Radiation laboratory University of Science and Technology of ChinaHefei 230029China Center for Functional Nanomaterials Brookhaven National LaboratoryUptonNY 11973-5000USA Physical Sciences Division Physical and Computational Sciences DirectoratePacific Northwest National LaboratoryRichlandWA 99352USA

hydrogenation of transition metal oxides offers a powerful platform to tailor physical functionalities as well as for potential applications in modern electronic technologies.An ideal nondestructive and efficient hydrogen incorporation approach is important for the realistic technological applications.We demonstrate the proton injection on SrCro3 thin films via an efficient low-energy hydrogen plasma implantation experiments,without destroying the original lattice framework.hydrogen ions accumu-late largely at the interfacial regions with amorphous character which extend about one-third of the total thickness.The hx.SrCro3(hSCO)thin films appear like exfoliated layers which however retain the fully strained state with distorted perovskite structure.Proton doping induces the change of Cr oxidation state from Cr^4+to Cr^3+in hSCO thin films and a transition from metallic to insulat-ing phase.Our investigations suggest an attractive platform in manipulating the electronic phases in proton-based approaches and may offer a potential peeling off strategy for nanoscale devices through low-energy hydrogen plasma implantation approaches.

关键词： transition metal oxide thin film metal-insulator transition hydrogenation