Despite the proficiency of lithium(Li)-7 NMR spectroscopy in delineating the physical and chemical states of Li metal electrodes,challenges in specimen preparation and interpretation impede its progress.In this study,...Despite the proficiency of lithium(Li)-7 NMR spectroscopy in delineating the physical and chemical states of Li metal electrodes,challenges in specimen preparation and interpretation impede its progress.In this study,we conducted a comprehensive postmortem analysis utilizing ^(7)Li NMR,employing a stan-dard magic angle spinning probe to examine protective-layer coated Li metal electrodes and LiAg alloy electrodes against bare Li metal electrodes within Li metal batteries(LMBs).Our investigation explores the effects of sample burrs,alignment with the magnetic field,the existence of liquid electrolytes,and precycling on the ^(7)Li NMR signals.Through contrasting NMR spectra before and after cycling,we identi-fied alterations in Li^(0) and Li^(+) signals attributable to the degradation of the Li metal electrode.Our NMR analyses decisively demonstrate the efficacy of the protective layer in mitigating dendrite and solid elec-trolyte interphase formation.Moreover,we noted that Li*ions near the Li metal surface exhibit magnetic susceptibility anisotropy,revealing a novel approach to studying diamagnetic species on Li metal elec-trodes in LMBs.This study provides valuable insights and practical guidelines for characterizing distinct lithium states within LMBs.展开更多
Converting solar energy into clean and sustainable chemical fuels is a promising strategy for exploiting renewable energy.The application of photocatalytic water splitting technology in hydrogen production is importan...Converting solar energy into clean and sustainable chemical fuels is a promising strategy for exploiting renewable energy.The application of photocatalytic water splitting technology in hydrogen production is important for sustainable energy development and environmental protection.In this study,for the first time,2D Cu7S4 co-catalysts were coupled on the surface of a CdS nanosheet photocatalyst by a one-step ultrasonic-assisted electrostatic self-assembly method at room temperature.The as-fabricated 2D^-2D CdS/Cu7S4 layered heterojunctions were demonstrated to be advanced composite photocatalysts that enhance the water splitting efficiency toward hydrogen production.The highest hydrogen evolution rate of the 2D^-2D CdS/2%Cu7S4 binary heterojunction photocatalyst was up to 27.8 mmol g^-1 h^-1 under visible light irradiation,with an apparent quantum efficiency of 14.7%at 420 nm,which was almost 10.69 times and 2.65 times higher than those of pure CdS nanosheets(2.6 mmol g^-1 h^-1)and CdS-2%CuS(10.5 mmol g^-1 h^-1),respectively.The establishment of the CdS/Cu7S4 binary-layered heterojunction could not only enhance the separation of photogenerated electron-hole(e--h+)pairs,improve the transfer of photo-excited electrons,and prolong the life-span of photo-generated electrons,but also enhance the light absorption and hydrogen-evolution kinetics.All these factors are important for the enhancement of the photocatalytic activity.Expectedly,the 2D^-2D interface coupling strategy based on CdS NSs can be extensively exploited to improve the hydrogen-evolution activity over various kinds of conventional semiconductor NSs.展开更多
基金the Basic Research Project(C123000,C210200,C310200,&C421000)of the Korea Basic Science Institute(KBSI)funded by the Korea Ministry of Science and ICT(MSIT)the Technology Development Program to Solve Climate Changes through the National Research Foundation of Korea(NRF)funded by MSIT(NRF-2021M1A2A2038141).O.H.Han thanks to Prof.I.S.Yang at Ewha Womans University for insightful discussion.
文摘Despite the proficiency of lithium(Li)-7 NMR spectroscopy in delineating the physical and chemical states of Li metal electrodes,challenges in specimen preparation and interpretation impede its progress.In this study,we conducted a comprehensive postmortem analysis utilizing ^(7)Li NMR,employing a stan-dard magic angle spinning probe to examine protective-layer coated Li metal electrodes and LiAg alloy electrodes against bare Li metal electrodes within Li metal batteries(LMBs).Our investigation explores the effects of sample burrs,alignment with the magnetic field,the existence of liquid electrolytes,and precycling on the ^(7)Li NMR signals.Through contrasting NMR spectra before and after cycling,we identi-fied alterations in Li^(0) and Li^(+) signals attributable to the degradation of the Li metal electrode.Our NMR analyses decisively demonstrate the efficacy of the protective layer in mitigating dendrite and solid elec-trolyte interphase formation.Moreover,we noted that Li*ions near the Li metal surface exhibit magnetic susceptibility anisotropy,revealing a novel approach to studying diamagnetic species on Li metal elec-trodes in LMBs.This study provides valuable insights and practical guidelines for characterizing distinct lithium states within LMBs.
基金the National Natural Science Foundation of China(21975084,51672089)Special Funding on Applied Science and Technology in Guangdong(2017B020238005)+2 种基金the State Key Laboratory of Advanced Technology for Material Synthesis and Processing(Wuhan University of Technology)(2015-KF-7)State Scholarship Fund of China Scholarship Council(200808440114)the Ding Ying Talent Project of South China Agricultural University for their support
文摘Converting solar energy into clean and sustainable chemical fuels is a promising strategy for exploiting renewable energy.The application of photocatalytic water splitting technology in hydrogen production is important for sustainable energy development and environmental protection.In this study,for the first time,2D Cu7S4 co-catalysts were coupled on the surface of a CdS nanosheet photocatalyst by a one-step ultrasonic-assisted electrostatic self-assembly method at room temperature.The as-fabricated 2D^-2D CdS/Cu7S4 layered heterojunctions were demonstrated to be advanced composite photocatalysts that enhance the water splitting efficiency toward hydrogen production.The highest hydrogen evolution rate of the 2D^-2D CdS/2%Cu7S4 binary heterojunction photocatalyst was up to 27.8 mmol g^-1 h^-1 under visible light irradiation,with an apparent quantum efficiency of 14.7%at 420 nm,which was almost 10.69 times and 2.65 times higher than those of pure CdS nanosheets(2.6 mmol g^-1 h^-1)and CdS-2%CuS(10.5 mmol g^-1 h^-1),respectively.The establishment of the CdS/Cu7S4 binary-layered heterojunction could not only enhance the separation of photogenerated electron-hole(e--h+)pairs,improve the transfer of photo-excited electrons,and prolong the life-span of photo-generated electrons,but also enhance the light absorption and hydrogen-evolution kinetics.All these factors are important for the enhancement of the photocatalytic activity.Expectedly,the 2D^-2D interface coupling strategy based on CdS NSs can be extensively exploited to improve the hydrogen-evolution activity over various kinds of conventional semiconductor NSs.
