Preparation Of Nickel-based Phosphide Catalyst And Its Application In Water Splitting

With the energy shortage and aggravation of environmental problems caused by the burning of fossil fuels,the energy crisis is getting more attention.The development and utilization of new energy has become an urgent need.As an efficient,clean and pollution-free new energy,hydrogen is generally regarded as an environmentally friendly fuel.In terms of hydrogen production,electrochemical water splitting has great advantages due to its simple operation process and short reaction time,while its development is limited due to its high overpotential and high energy consumption.At present,the main commercial use is Pt base,Ru/Ir base oxides and other precious metal catalysts.However,the high price of the precious metal itself and the low reserves of resources are difficult to meet the actual demand for large-scale production.Therefore,it is an urgent matter to explore the efficient and stable electrocatalyst to meet the application in industrial production.Transition metals have attracted attention because of their rich content and low price,especially transition metal phosphide has advantages of low cost and high intrinsic activity.However,the problems of low catalytic efficiency and poor cyclic stability of non-noble metal catalysts need to be solved.To solve these problems,in this paper,the modified nickel-based phosphide catalysts were prepared by simple hydrothermal and phosphating methods,respectively:Mo-Ni₂P/CC,V-Ni Co P/CC and Ni₅P₄@Fe V LDH.The research contents are as follows:（1）A kind of molybdenum doped nickel phosphide hydrogen evolution catalytic material（Mo-Ni₂P/CC）in fresh water or seawater was prepared by using Mo element as doping element.The optimal catalyst material was synthesized by adjusting the proportion of doping elements.The crystal structure,morphology,microstructure and electrochemical properties of the samples were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）and Chenhua electrochemical testing system.A series of tests and characterization results show that Mo-Ni₂P/CC catalytic materials display excellent catalytic activity of hydrogen evolution reaction（HER）in both fresh water and seawater.（2）A kind of vanadium doped nickel-cobalt phosphide catalyst material（V-Ni Co P/CC）for HER in alkaline environment was prepared by using V element as doping element.The best Ni Co P/CC catalytic material was obtained by adjusting the molar ratio of Ni and Co element,and then the catalytic material with different V doping was obtained by changing the ratio of vanadium doping element.The results were characterized by XRD,SEM and TEM.The test results show that the catalyst material exhibits the best hydrogen evolution performance when the ratio of Ni to Co is 1:1 and the doping amount of vanadium is 10%.（3）Nickel phosphide supported Fe V precursor catalyst material（Ni₅P₄@Fe V LDH）was synthesized by hydrothermal method with nickel phosphide as substrate.The structure,morphology and valence distribution were studied by XRD,SEM,TEM and XPS.The electrochemical test results show that the catalytic material loaded with Fe V LDH has excellent catalytic performance in oxygen evolution reaction（OER）.At the same time,after adding urea to alkaline solution,the urea oxidation reaction（UOR）also shows that the catalytic material has excellent catalytic performance at reducing the anodic reaction potential.