The Controllable Electrochemical Preparation And Electrocatalytic Hydrogen Evolution Performance Of Ni-based Cathode

With the aggravation of energy crisis and environmental pollution,renewable hydrogen energy as a kind of clean energy has attracted much attention.So far,electrocatalytic hydrogen evolution is still the most popular technology to acquire hydrogen.Among them,the cathode electrocatalyst is the core of electrocatalytic hydrogen evolution system.In addition to platinum and other rare precious metals,more and more nickel-based catalysts have been studied.The preparation of catalysts is one of the research hot topics.Among them,the electrochemical method has received much attention because of its many advantages.For example,it is simple to operate,time-saving,easy to be implemented at room temperature,and avoids the use of binders.Moreover,the deposition modes of the electrochemical method are diversified,and the chemical content and proportion of deposited layer components,the thickness and morphology of deposited layer can be adjusted by controlling the variety of parameters,such as,deposition potential or current value,scanning speed,and pulse period,pulse width,pulse amplitude in the pulse method.In this work,two nickel-based catalysts were prepared by electrochemical method,which provided an effective pathway for the controllable preparation of hydrogen evolution catalysts.This article mainly includes the following two aspects:1. In order to improve the activity of hydrogen evolution,Ni-Fe-P/Ni NP catalyst was prepared by potentiostatic method and electrochemical pulse method.First,the Ni nanopore substrate on titanium steel was prepared by potentiostatic method using the technique of deposition-dissolution,aiming to increase the electrochemical active surface area,.Second,Ni-Fe-P catalysts were deposited on the Ni nanopore substrate with different pulse period cycles by electrochemical pulse method in order to form the expected disordered porous structure,which exposed more active surface area to the solution.Then the catalytic activity of the as-prepared electrodes for hydrogen evolution was evaluated in 1 M KOH solution,and its surface morphology,structure and composition were characterized and analyzed.When the pulse period cycles were 3000 in the deposition step,the overpotential of the as-prepared catalyst（Ni-Fe-P/Ni NP-3000）was the least.The current density reached 10 m A/cm²and 100m A/cm²,the overpotentials were corresponding 58 m V and 141 m V,respectively,and the Tafel slope was 84.97 m V·dec^-1.2. In this study,the magnetic field was introduced during the deposition of nickel due to the magnetic properties of nickel element,so as to improve the hydrogen evolution activity by changing the surface morphology and deposition amount of nickel deposition layer.First,the potentiostatic method was used to deposit the Ni catalyst on titanium steel under the conditions of different magnetic field,and then the effects of the magnetic field on its morphology,deposition amount,electrochemical active surface area,conductivity and the hydrogen evolution performance were investigated.The results showed that when the titanium steel was parallel to the magnetic field line,the overpotential of deposited nickel was the least at a distance of 7.5cm from the magnet,which was 23 m V,and the Tafel slope was56.76 m V dec^-1.When the titanium steel was perpendicular to the magnetic field line,the overpotential of deposited nickel was the least at a distance of 12.5cm from the magnet,which was 149 m V,and the Tafel slope was 72.32 m V dec^-1.