Two series of 3d-Gd mixed-metal phosphonate complexes with either only two gadolinium centers such as{Gd2},{Ni2Gd2},{Co4Gd2},{Co8Gd2},{Fe6Gd2},and{Fe17Gd2}or more than two gadoliniums such as{Co8Gd4},{Mn8Gd4},{Co4Gd6}...Two series of 3d-Gd mixed-metal phosphonate complexes with either only two gadolinium centers such as{Gd2},{Ni2Gd2},{Co4Gd2},{Co8Gd2},{Fe6Gd2},and{Fe17Gd2}or more than two gadoliniums such as{Co8Gd4},{Mn8Gd4},{Co4Gd6},{Mn4Gd6},{Co6Gd8},{Ni5Gd8},{Ni6Gd6},{Co8Gd8},and{Mn9Gd9}have been solvothermally prepared and magnetothermally studied.The nearly identical environments of the Gd(III)dimer in thefirst series allow us to qualitatively analyze the effect of magnetic exchange coupling on the magne-tocaloric effect(MCE).By doubling,tripling,or quadrupling of the Gd(III)centers,the second series of 3d-Gd mixed-metal complexes was built to further test the other effects of exchange couplings on MCE in more complicated circumstances.For the antiferromagnetic coupling cases,the results are nearly identical but diversify when topological spin frustrations are created,whose massive low-lying excited spin states help enhance MCE.For presumably ferromagnetically coupled ones,albeit are rare in phosphonate complexes,they do exhibit excellent MCE.Meanwhile,the com-plexes with weakly coupled metal centers serve as excellent examples for studying the effect of molecular mass on MCE when its magnitude is expressed in the unit of Joule per kilogram,from which we can see the values are directly proportional to the percentage of the Gd(III)ions in molecular weight.展开更多
In this study,Ni catalysts supported on Pr-doped Ce O_(2) are studied for the CO_(2) methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evalu...In this study,Ni catalysts supported on Pr-doped Ce O_(2) are studied for the CO_(2) methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated.It is shown,that Pr^(3+)ions can substitute Ce^(4+)ones in the support lattice,thereby introducing a high population of oxygen vacancies,which act as active sites for CO_(2) chemisorption.Pr doping can also act to reduce the crystallite size of metallic Ni,thus promoting the active metal dispersion.Catalytic performance evaluation evidences the promoting effect of low Pr loadings(5 at%and 10 at%)towards a higher catalytic activity and lower CO_(2) activation energy.On the other hand,higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population,thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.展开更多
Nickel–yttria stabilized zirconia(Ni–YSZ)cermet is the most commonly used anode in solid oxide fuel cells(SOFCs).The current article provides an insight into parameters which affect cell performance and stability by...Nickel–yttria stabilized zirconia(Ni–YSZ)cermet is the most commonly used anode in solid oxide fuel cells(SOFCs).The current article provides an insight into parameters which affect cell performance and stability by reviewing and discussing the related publications in this field.Understanding the parameters which affect the microstructure of Ni–YSZ such as grain size(Leng et al 2003 J.Power Sources 11726–34)and ratio of Ni to YSZ,volume fraction of porosity,pore size and its distribution,tortuosity factor,characteristic pathway diameter and density of triple phase boundaries is the key to designing a fuel cell which shows high electrochemical performance.Lack of stability has been the main barrier to commercialization of SOFC technology.Parameters influencing the degradation of Ni–YSZ supported SOFCs such as Ni migration inside the anode during prolonged operation are discussed.The longest Ni-supported SOFC tests reported so far are examined and the crucial role of chromium poisoning due to interconnects,stack design and operating conditions in degradation of SOFCs is highlighted.The importance of calcination and milling of YSZ to development of porous structures suitable for Ni infiltration is explained and several methods to improve the electrochemical performance and stability of Ni–YSZ anode supported SOFCs are suggested.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:21971203,22375157State Key Laboratory of Electrical Insulation and Power Equipment,Grant/Award Numbers:EIPE23402,EIPE23405+3 种基金Special Support Plan of Shaanxi Province for Young Top-notch Talent and the Fundamental Research Funds for Central Universities,Grant/Award Number:xtr052023002Medical-Engineering Cross Project of the First Affiliated Hospital of XJTU,Grant/Award Number:QYJC02Spanish MICINN,Grant/Award Number:PID2021-124734OB-C21“Scientists+Engineers”Team Building Project of Qin Chuang Yuan,Grant/Award Number:2022KXJ-088。
文摘Two series of 3d-Gd mixed-metal phosphonate complexes with either only two gadolinium centers such as{Gd2},{Ni2Gd2},{Co4Gd2},{Co8Gd2},{Fe6Gd2},and{Fe17Gd2}or more than two gadoliniums such as{Co8Gd4},{Mn8Gd4},{Co4Gd6},{Mn4Gd6},{Co6Gd8},{Ni5Gd8},{Ni6Gd6},{Co8Gd8},and{Mn9Gd9}have been solvothermally prepared and magnetothermally studied.The nearly identical environments of the Gd(III)dimer in thefirst series allow us to qualitatively analyze the effect of magnetic exchange coupling on the magne-tocaloric effect(MCE).By doubling,tripling,or quadrupling of the Gd(III)centers,the second series of 3d-Gd mixed-metal complexes was built to further test the other effects of exchange couplings on MCE in more complicated circumstances.For the antiferromagnetic coupling cases,the results are nearly identical but diversify when topological spin frustrations are created,whose massive low-lying excited spin states help enhance MCE.For presumably ferromagnetically coupled ones,albeit are rare in phosphonate complexes,they do exhibit excellent MCE.Meanwhile,the com-plexes with weakly coupled metal centers serve as excellent examples for studying the effect of molecular mass on MCE when its magnitude is expressed in the unit of Joule per kilogram,from which we can see the values are directly proportional to the percentage of the Gd(III)ions in molecular weight.
基金support of this work by the project“Development of new innovative low carbon energy technologies to improve excellence in the Region of Western Macedonia”(MIS 5047197)which is implemented under the Action“Reinforcement of the Research and Innovation Infrastructure”funded by the Operational Program“Competitiveness,Entrepreneurship and Innovation”(NSRF 2014-2020)co-financed by Greece and the European Union(European Regional Development Fund)。
文摘In this study,Ni catalysts supported on Pr-doped Ce O_(2) are studied for the CO_(2) methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated.It is shown,that Pr^(3+)ions can substitute Ce^(4+)ones in the support lattice,thereby introducing a high population of oxygen vacancies,which act as active sites for CO_(2) chemisorption.Pr doping can also act to reduce the crystallite size of metallic Ni,thus promoting the active metal dispersion.Catalytic performance evaluation evidences the promoting effect of low Pr loadings(5 at%and 10 at%)towards a higher catalytic activity and lower CO_(2) activation energy.On the other hand,higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population,thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.
基金The authors would like to acknowledge Future Energy Systems Research Initiative(Grant Number RES0031233)grant PID2019-107106RB-C32 funded by MCIN/AEI/10.13039/50110001103 for financial support of the research carried out at the University of Alberta and Instituto de Nanociencia y Materiales de Aragón(CSIC-Unizar)and during preparation of the current manuscript.
文摘Nickel–yttria stabilized zirconia(Ni–YSZ)cermet is the most commonly used anode in solid oxide fuel cells(SOFCs).The current article provides an insight into parameters which affect cell performance and stability by reviewing and discussing the related publications in this field.Understanding the parameters which affect the microstructure of Ni–YSZ such as grain size(Leng et al 2003 J.Power Sources 11726–34)and ratio of Ni to YSZ,volume fraction of porosity,pore size and its distribution,tortuosity factor,characteristic pathway diameter and density of triple phase boundaries is the key to designing a fuel cell which shows high electrochemical performance.Lack of stability has been the main barrier to commercialization of SOFC technology.Parameters influencing the degradation of Ni–YSZ supported SOFCs such as Ni migration inside the anode during prolonged operation are discussed.The longest Ni-supported SOFC tests reported so far are examined and the crucial role of chromium poisoning due to interconnects,stack design and operating conditions in degradation of SOFCs is highlighted.The importance of calcination and milling of YSZ to development of porous structures suitable for Ni infiltration is explained and several methods to improve the electrochemical performance and stability of Ni–YSZ anode supported SOFCs are suggested.
