New energy development is essential to achieving carbon peaks and neutrality and promoting green technological innovation.Identifying the causal relationship between new energy demonstration city construction and gree...New energy development is essential to achieving carbon peaks and neutrality and promoting green technological innovation.Identifying the causal relationship between new energy demonstration city construction and green technological innovation is crucial for the expansion and promotion of new energy demonstration cities.In this study,we take the construction of new energy demonstration cities as a quasi-natural experiment,study their impact on green technological innovation using difference-indifference(DID),and conduct a robustness test using DID after propensity score matching(PSM-DID).The research results indicate the following:First,energy structure optimization can significantly improve the level of urban green technological innovation(this result was shown to be valid using PSM-DID and other tests involving the effects of placebo and instrumental variables).Second,new energy demonstration city construction mainly improves the level of urban green technological innovation through technology research and development,the improvement of the industrial innovation environment,and the promotion of environmental performance.Third,the impact of energy structure optimization on green technological innovation has regional,financial,and economic development heterogeneity.Finally,new energy demonstration city policy affects the flow of capital,labor,technology,and other production factors to pilot areas according to new energy demonstration city policy,forming a“siphon effect”.The carbon reduction effect of new energy demonstration city construction is greater than its pollution reduction effect.Given the results of the study,policy recommendations to promote the expansion of new energy demonstration cities are proposed.展开更多
Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the explo...Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal FeSe nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that FeSe undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized FeSe nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)Se after full potassiation can be converted back into the original FeSe phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs.展开更多
基金the National Social Science Fund of China(22CJL004).
文摘New energy development is essential to achieving carbon peaks and neutrality and promoting green technological innovation.Identifying the causal relationship between new energy demonstration city construction and green technological innovation is crucial for the expansion and promotion of new energy demonstration cities.In this study,we take the construction of new energy demonstration cities as a quasi-natural experiment,study their impact on green technological innovation using difference-indifference(DID),and conduct a robustness test using DID after propensity score matching(PSM-DID).The research results indicate the following:First,energy structure optimization can significantly improve the level of urban green technological innovation(this result was shown to be valid using PSM-DID and other tests involving the effects of placebo and instrumental variables).Second,new energy demonstration city construction mainly improves the level of urban green technological innovation through technology research and development,the improvement of the industrial innovation environment,and the promotion of environmental performance.Third,the impact of energy structure optimization on green technological innovation has regional,financial,and economic development heterogeneity.Finally,new energy demonstration city policy affects the flow of capital,labor,technology,and other production factors to pilot areas according to new energy demonstration city policy,forming a“siphon effect”.The carbon reduction effect of new energy demonstration city construction is greater than its pollution reduction effect.Given the results of the study,policy recommendations to promote the expansion of new energy demonstration cities are proposed.
基金This work was supported by the National Key R&D Program of China(Grant No.2018YFB1304902)the National Natural Science Foundation of China(Grant Nos.12004034,U1813211,22005247,11904372,51502007,52072323,52122211,12174019,and 51972058)+1 种基金the Gen-eral Research Fund of Hong Kong(Project No.11217221)China Postdoctoral Science Foundation Funded Project(Grant No.2021M690386).
文摘Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal FeSe nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that FeSe undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized FeSe nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)Se after full potassiation can be converted back into the original FeSe phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs.
