A polyhedral metal-organic framework(MOF)JLU-Liu40-In based on dual secondary building units(SBUs)of mononuclear and binuclear paddlewheel indium has been prepared with a nitrogen-rich tetracarboxylic acid ligand unde...A polyhedral metal-organic framework(MOF)JLU-Liu40-In based on dual secondary building units(SBUs)of mononuclear and binuclear paddlewheel indium has been prepared with a nitrogen-rich tetracarboxylic acid ligand under solvothermal conditions.Since the framework possesses large surface areas with multiple polyhedral cages,abundant open metal sites(OMSs)and Lewis basic sites(LBSs),it exhibits high performance for gas adsorption.In addition,through post-synthetic metal-ion metathesis in a single-crystal-to-single-crystal(SCSC)process,JLU-Liu40-In/Cu has been obtained by selectively substituting the paddlewheel In(Ⅲ)ions with Cu(Ⅱ)ions without replacing the mononuclear In(Ⅲ).The framework remains in the form of a single crystal throughout the process.It is worth noting that the metal-ion metathesis approach constructs JLU-Liu40-In/Cu with a significant improvement in thermal stability and gas sorption and separation.展开更多
Post-transition-metal chalcogenides,such as SnSe,SnSe_(2),In_(4)Se_(3),and In_(2)Se_(3),have attracted renewed attention as promising thermoelectric materials mainly due to their inherent low lattice thermal conductiv...Post-transition-metal chalcogenides,such as SnSe,SnSe_(2),In_(4)Se_(3),and In_(2)Se_(3),have attracted renewed attention as promising thermoelectric materials mainly due to their inherent low lattice thermal conductivities,originating from the atomically layered structure.Herein,we demonstrate the enhanced thermoelectric transport properties of n-type InSe in an effort to search for new thermoelectric materials within post-transition-metal chalcogenide systems.By Si doping at the In site,significantly enhanced electrical conductivity is obtained,mainly due to the simultaneous increase in both carrier concentration and mobility.Meanwhile,the large Seebeck coefficient is maintained despite the increase of carrrier concentration with Si doping.Based on theoretical considerations for band structure change by Si doping,this unconventional trade-off between electrical conductivity and Seebeck coefficient is due to the generation of heavy flat energy levels near the conduction band minimum in the presence of Si at the In site.The doped Si also acts as an effective point defect phonon scattering center,resulting in reduced lattice thermal conductivity.Due to this synergetic effect,a 210%improved thermoelectric figure of merit(zT)of 0.14 at 795 K compared with pristine InSe was obtained by 7%Si doping.展开更多
基金financial support from the National Natural Science Foundation of China(No.21771078 and 21621001)the 111 Project(B17020)+2 种基金the National Key Research and Development Program of China(2016YFB0701100)the Fundamental Research Funds for the Central Universities of Ocean University of China(201813031)the Shandong Province Natural Foundation of China(ZR2019BB033).
文摘A polyhedral metal-organic framework(MOF)JLU-Liu40-In based on dual secondary building units(SBUs)of mononuclear and binuclear paddlewheel indium has been prepared with a nitrogen-rich tetracarboxylic acid ligand under solvothermal conditions.Since the framework possesses large surface areas with multiple polyhedral cages,abundant open metal sites(OMSs)and Lewis basic sites(LBSs),it exhibits high performance for gas adsorption.In addition,through post-synthetic metal-ion metathesis in a single-crystal-to-single-crystal(SCSC)process,JLU-Liu40-In/Cu has been obtained by selectively substituting the paddlewheel In(Ⅲ)ions with Cu(Ⅱ)ions without replacing the mononuclear In(Ⅲ).The framework remains in the form of a single crystal throughout the process.It is worth noting that the metal-ion metathesis approach constructs JLU-Liu40-In/Cu with a significant improvement in thermal stability and gas sorption and separation.
基金supported by a grant from the Korean National Research Funds(NRF-2017R1D1A1B03034257&NRF-2018R1D1A1B07042573)This research was also supported by Low-dimensional Materials Genome Development by Korea Research Institute of Standards and Science(KRISS-2018-18011084).
文摘Post-transition-metal chalcogenides,such as SnSe,SnSe_(2),In_(4)Se_(3),and In_(2)Se_(3),have attracted renewed attention as promising thermoelectric materials mainly due to their inherent low lattice thermal conductivities,originating from the atomically layered structure.Herein,we demonstrate the enhanced thermoelectric transport properties of n-type InSe in an effort to search for new thermoelectric materials within post-transition-metal chalcogenide systems.By Si doping at the In site,significantly enhanced electrical conductivity is obtained,mainly due to the simultaneous increase in both carrier concentration and mobility.Meanwhile,the large Seebeck coefficient is maintained despite the increase of carrrier concentration with Si doping.Based on theoretical considerations for band structure change by Si doping,this unconventional trade-off between electrical conductivity and Seebeck coefficient is due to the generation of heavy flat energy levels near the conduction band minimum in the presence of Si at the In site.The doped Si also acts as an effective point defect phonon scattering center,resulting in reduced lattice thermal conductivity.Due to this synergetic effect,a 210%improved thermoelectric figure of merit(zT)of 0.14 at 795 K compared with pristine InSe was obtained by 7%Si doping.
