The Synthesis Of Transition Metal Compounds And Their Electrochemical Properties

An important way to solve the energy crisis and environmental problems facing mankind is to develop new energy sources.Among them,hydrogen production from electrochemical water splitting is an important method and has attracted great attention.However,the reaction of hydrogen evolution and oxygen evolution of electrolytic water is a multi-electronic and multi-step reaction,which brings high overpotential and energy consumption during water splitting.The most simple way to reduce the energy consumption of water splitting is to find electrocatalysts that can reduce the overpotential of anodic oxygen evolution reaction and cathodic hydrogen evolution reaction.As potential electrocatalytic materials,various strategies have been applied to the design and synthesis of transition metal compounds.The synthesis of multicomponent catalysts provides a correct direction for discovering high performance catalysts.The whole work in this thesis can be summarized as follows:1.Ni_4.5Fe_4.5S₈/Ni₃S₂ film with micrometer thickness on bulk substrate was synthesized by a simple one-step hydrothermally assisted sulfurization of Ni₃Fe alloy foam for oxygen evolution reaction?OER?in basic media.Benefiting from the synergetic effect of bicomponent,reduced interfacial resistance between electrocatalyst and metal substrate,more exposed catalytic sites on microstructured film,the as-prepared electrocatalyst(Ni_4.5Fe_4.5S₈/Ni₃S₂?Ni₃Fe)behaves as a high-efficient and robust oxygen evolution electrode with felicitous current density in alkaline electrolyte?1 M KOH?.It only requires an overpotential of 264 mV to drive 100 mA.cm^-2 with its catalytic activity being maintained for at least 20 h in 1.0 M KOH.In near future,this kind of synthesis strategy can be easily extended to investigate various electrocatalysts derived from 3D alloyed foam with various ratios of different component,opening new avenue for understanding the relationship between materials property and electrochemical performance.2.The design and synthetic of high-performance hydrogen evolution reaction?HER?catalysts requires an overall consideration of intrinsic activity and electric conductivity as well as stability.Here,direct growth of metallic CoMoO₄ nanosheets on 3D Co foam by one-step hydrothermal reaction.The structural characterization and electrochemical properties of the material were determined.Benefiting from the strong interactions between Co and CoMoO₄,the resultant CoMoO₄?Co electrode has the fastest charge transfer process,coincident with the best HER performance,it requires a low overpotential of only 187 mV to deliver a current density of 100 mA.cm^-2.In addition,the material exhibited high electrochemical stability,evidenced by the current density of 20 mA.cm^-2 being maintained for at least 20 h in 1 M KOH.