Design And Synthesis Of Nickel/cobalt-based Chalcogenide For Electrocatalysis

With the global energy crisis and environmental problems intensifying,the development of clean energy has become an imminent challenge that attracts widespread attention.Under the premise of pursuing zero carbon emissions,the renewable energy hydrogen energy is considered to be the most promising energy carrier to replace traditional fossil energy,due to high energy density and good environmental compatibility.To realize the industrialization of hydrogen energy,the first thing to face is the serious obstacle of low energy conversion efficiency.Currently electrochemical water splitting and fuel cells are two advanced hydrogen energy conversion technologies with promising prospect.In these two technologies,the hydrogen evolution reaction?HER?and oxygen evolution reaction?OER?in the water electrolysis process and the oxygen reduction reaction?ORR?in the fuel cell are the key links.They are all determinants of the overall energy conversion efficiency in the energy system.To minimize the overvoltages of HER,OER and ORR,it is necessary to develop effective catalysts to enhance the reaction rate and economic benefits.At present,the precious metal materials such as Ru,Ir,and Pt are the most effective catalysts.However,high-cost and scarcity of which are bound to hinder widespread application and long-term development of energy conversion technology.To meet a need for large scale application,it is essential to design and develop efficient catalysts with low cost and long-term stability.Various transition metal-based materials?including Ni,Co,Fe,Mo,V,Cu,etc.?are widely used as advanced electroactive catalysts.Compared with precious metals,nickel and cobalt-based nanostructured materials are rich in resources and low in cost,making them ideal choices for electrocatalysts.In this paper,nickel-based and cobalt-based nanostructured materials are selected as research topic.First,a comprehensive analysis and summary of the reaction principles of HER,OER,and ORR are provided,and the factors restricting electrocatalytic performance are discussed.Then,nickel-based and cobalt-based nanocatalytic materials with a specific composition and morphology are designed and synthesized.The overpotential of related reaction is reduced and multifunctional catalysis for HER,OER and ORR has been realized.On the one hand,the research work in this paper provides low-cost multifunctional electrocatalytic materials for efficient energy conversion.On the other hand,the proposed synthesis strategy may throw light on the research of other functional materials with diverse applications.The research content of this article is summarized as follows:?1?We used a solvothermal method to in-situ grow Co-doped NiSe nanoflowers?Co-NiSe/NF?on a foamed nickel substrate,and systematically studied the OER catalytic performance of the material in alkaline media.The results show that the overpotential required for Co-NiSe/NF at a current density of 100 mA cm^-2is only380 mV.And the catalytic stability is satisfactory.The prepared Co-NiSe/NF electrode possesses more catalytic active sites and better electrical conductivity than the intrinsic NiSe electrode,showing significantly improved OER catalytic activity.?2?Using layered carbon nitride?g-C₃N₄?as a sacrificial template,Co₉S₈/Co was encapsulated in N-doped graphite carbon tube?Co₉S₈/Co-NCNT?by one-step pyrolysis.The results show that under basic conditions,Co₉S₈/Co-NCNT displays excellent performance for ORR(E_1/2?0.93 V),HER??_j=10?196 mV?and OER??_j=10?450 mV?with good catalytic stability.Compared with intrinsic Co₉S₈,trifunctional catalytic activity of Co₉S₈/Co-NCNT is significantly improved.