The underlying spin-related mechanism remains unclear,and the rational manipulation of spin states is challenging due to various spin configurations under different coordination conditions.Therefore,it is urgent to st...The underlying spin-related mechanism remains unclear,and the rational manipulation of spin states is challenging due to various spin configurations under different coordination conditions.Therefore,it is urgent to study spin-dependent oxygen evolution reaction(OER)performance through a controllable method.Herein,we adopt a topochemical reaction method to synthesize a series of selenides with eg occupancies ranging from 1.67 to 1.37.The process begins with monoclinic-CoSeO_(3),featuring a distinct laminar structure and Co-O6 coordination.The topochemical reaction induces significant changes in the crystal field's intensity,leading to spin state transitions.These transitions are driven by topological changes from a Co-O-Se-O-Co to a Co-Se-Co configuration,strengthening the crystalline field and reducing eg orbital occupancy.This reconfiguration of spin states shifts the rate-determining step from desorption to adsorption for both OER and the hydrogen evolution reaction(HER),reducing the potential-determined step barrier and enhancing overall catalytic efficiency.As a result,the synthesized cobalt selenide exhibits significantly enhanced adsorption capabilities.The material demonstrates impressive overpotentials of 35 mV for HER,250 mV for OER,and 270 mV for overall water splitting,indicating superior catalytic activity and efficiency.Additionally,a negative relation between eg filling and OER catalytic performance confirms the spin-dependent nature of OER.Our findings provide crucial insights into the role of spin state transitions in catalytic performance.展开更多
Developing high-performance bifunctional catalysts toward hydrogen evolution reaction(HER) and oxygen evolution reaction(OER) is essential to enhance water splitting efficiency for large-scale hydrogen production. Nei...Developing high-performance bifunctional catalysts toward hydrogen evolution reaction(HER) and oxygen evolution reaction(OER) is essential to enhance water splitting efficiency for large-scale hydrogen production. Neither noble metal Pt nor transition metal compounds show satisfactory performances for both HER and OER simultaneously. Here, we prepared a three-dimensional Pt-Ni3 Se2@NiOOH/NF(PNOF) hybrid catalyst via in-situ growth strategy. Benefitting from the self-supported structure and oxygen vacancies on the surface of NiOOH nanosheets, the PNOF electrode shows remarkably catalytic performance for dual HER and OER. The overall water electrolyzer using PNOF as anode and cathode can achieve a current density of10 mA cm^-2 at a low voltage of 1.52 V with excellent long-term stability, which is superior to precious metal catalysts of Pt/C and Ir/C. This study provides a promising strategy for preparing bifunctional catalysts with high performance.展开更多
文摘The underlying spin-related mechanism remains unclear,and the rational manipulation of spin states is challenging due to various spin configurations under different coordination conditions.Therefore,it is urgent to study spin-dependent oxygen evolution reaction(OER)performance through a controllable method.Herein,we adopt a topochemical reaction method to synthesize a series of selenides with eg occupancies ranging from 1.67 to 1.37.The process begins with monoclinic-CoSeO_(3),featuring a distinct laminar structure and Co-O6 coordination.The topochemical reaction induces significant changes in the crystal field's intensity,leading to spin state transitions.These transitions are driven by topological changes from a Co-O-Se-O-Co to a Co-Se-Co configuration,strengthening the crystalline field and reducing eg orbital occupancy.This reconfiguration of spin states shifts the rate-determining step from desorption to adsorption for both OER and the hydrogen evolution reaction(HER),reducing the potential-determined step barrier and enhancing overall catalytic efficiency.As a result,the synthesized cobalt selenide exhibits significantly enhanced adsorption capabilities.The material demonstrates impressive overpotentials of 35 mV for HER,250 mV for OER,and 270 mV for overall water splitting,indicating superior catalytic activity and efficiency.Additionally,a negative relation between eg filling and OER catalytic performance confirms the spin-dependent nature of OER.Our findings provide crucial insights into the role of spin state transitions in catalytic performance.
基金supported by the National Natural Science Foundation of China(51804216,51472178 and U1601216)Tianjin Natural Science Foundation(16JCYBJC17600)and Shen-zhen Science and Technology Foundation(JCYJ20170307145703486)
文摘Developing high-performance bifunctional catalysts toward hydrogen evolution reaction(HER) and oxygen evolution reaction(OER) is essential to enhance water splitting efficiency for large-scale hydrogen production. Neither noble metal Pt nor transition metal compounds show satisfactory performances for both HER and OER simultaneously. Here, we prepared a three-dimensional Pt-Ni3 Se2@NiOOH/NF(PNOF) hybrid catalyst via in-situ growth strategy. Benefitting from the self-supported structure and oxygen vacancies on the surface of NiOOH nanosheets, the PNOF electrode shows remarkably catalytic performance for dual HER and OER. The overall water electrolyzer using PNOF as anode and cathode can achieve a current density of10 mA cm^-2 at a low voltage of 1.52 V with excellent long-term stability, which is superior to precious metal catalysts of Pt/C and Ir/C. This study provides a promising strategy for preparing bifunctional catalysts with high performance.
