Performance Engineering Of Efficient Catalysts For Electrolytic Water Technology

Hydrogen has been regarded as one of the most promising fossil fuel alternatives due to the advantages of non-polluting and high energy density.Electrochemical water splitting has recently emerged as a prospective method to produce hydrogen via the oxygen evolution reaction（OER）and hydrogen evolution reaction（HER）.However,the sluggish HER/OER kinetics require high overpotential to overcome the barriers.Typically,state-of-the-art electrocatalysts are mainly noble metal materials,such as Ru/Ir O₂ for OER and Pt for HER,which limited the large-scale application of water splitting technology.At present,transition metal-based materials have been extensively investigated as electrocatalysts for water splitting.In this thesis,three kinds of trasition mateal based catalysts supported on CC with superior performance for HER and OER were prepared through solvothermal and high-temperature pyrolysis method.The main contents of this thesis are as follows:I.Co V precursors with nanorod-like morphology were prepared by hydrothermal method,and then V-doped Co P catalysts（VCo-P-2）were obtained by using phosphating method.The influence of amount of sodium hypophosphite on electroactivity was studied.It was found that the introduction of V not only changed the chemical environment of Co and P elements in the material,but also proved the electrochemically active surface area and electrical conductivity of the material.The optimized catalyst（VCo-P-2）has excellent activity.II.Ni-MOF precursors on Ni（OH）₂ templates was firstly prepared by solvothermal method using Ni（OH）₂ as templates.Then the Ni-MOF precursors was selenized with Se powder at high temperature to obtain Fe₃Se₄@Ni Se₂ heterostructured electrocatalyst(Fe Ni-Se-2.The morphology and composition of the materials were tuned by controlling the mass ratio of selenium powder to precursor samples.The prepared catalysts displayed high performance for HER as well as OER,which provided a current density of 10 m A cm^-2 at the overpotential of only 160 m V and 134m V,respectively,and have excellent stability.III.The Zn Ni MOF precursor was prepared by the solvothermal method,and then the Zn Se@Ni Se₂ catalyst（Zn Ni Se-2）was prepared by the selenization treatment.By adjusting the conditions of the selenization reaction,it was found that the introduction of Zn Se could modulate the chemical environment of Ni and Se elements,and the obtained Zn Ni Se-2 catalysts required only 157 m V and 189 m V overpotentials to provide a current density of 10m A cm^-2.The morphological structure of the materials was characterized by SEM,TEM,XPS and XRD,and then the electrocatalytic activity and stability of the materials were characterized using CV,LSV,IT and EIS electrochemical techniques.The final results demonstrate the excellent performance of the prepared catalysts in electrochemical catalysis.