Performance Engineering Of Multifunctional Transition Metal-based Electrocatalysts

The consumption of non-renewable energy,such as coal,oil,and natural gas,result in sevious energy crisis and environmental issues in recent years.Therefore,these issues have aroused wide concern all over the world.To solve these problems,hydrogen energy has been paid numerous attention due to its high power desnsity and non-pollution feature.Electrocatalytic water splitting including oxygen evolution reaction（OER）and hydrogen evolution reaction（HER）reactions is regarded as a potential way to generate hydrogen.However,the noble metal base electrocatalysts such as Pt and Ru O₂ are used to lower the cell voltage of water splitting.Thus,this impedes the large-scale application of water splitting technology.Transition metal-based materials（such as Fe,Mo,nickel,etc.）have been widely used in the field of electrocatalysis because of their low price and high conductivity.In this thesis,three kinds of bifunctional electrocatalysts supported on conductive matrix carbon cloth were prepared by electrodeposition,hydrothermal and high-temperature calcination method.The main content contains the following three parts:1,A simple two-step electrodeposition method was used.The first step was to synthesize Ni Fe-LDH nanosheets with high specific surface area.Then,Ni₄Mo nanoparticles embedded in Ni Fe-LDH nanosheets was prepared by regulating reaction temperature and deposition potential.The results indicated that the material had a large amount of disordered structure and exhibited excellent activity for HER and OER.2,Firstly,Ni Mo O₄ nanorods supported on carbon cloth（Ni Mo O₄/CC）was synthesized by solvothermal method.Next,Ni Mo O₄/CC was used as precursor and 1,1’-ferrocenedicarboxylic acid as ligand to synthesize MOF loaded om Ni Mo O₄ material.Finally,the samples were selenized in a tube furnace at 450℃to obtain Fe-doped nickel selenide and molybdenum selenide heterogeneous material（Fe-Ni Se₂/Mo Se₂）.Fe-Ni Se₂/Mo Se₂ as bifunctional electrocatalyst displays good performance by adjusting the electronic structure of elements and conductivity.3,V doped nickel-molybdenum oxide samples was prepared by solvothermal method,and then the precursor was treated by the following two steps respectively.First,the material went through sulfide reaction using thioacetamide as sulfide regent.Finally,V-doped Ni_2.5Mo₆S_7.5/Mo₃Se₄ with excellent activity for HER and OER was prepared by selenization treatment.It required 1.54 V to drive the current density of 10 m A cm^-2 for the whole water splitting.