Electrocatalytic Hydrogen Evolution Of Three Dimensional Electrode Based On Macroporous Electrically Conductive Network

Hydrogen,as a renewable environmental friendly energy resource,has attracted intense attention.Hydrogen production by electrolysis of water is the potential method due to its environmentally-friendly process which neither cause environmental pollution nor consume non-renewable energy resources.In this case,a series of research work has been carried on the electrolytic hydrogen evolution of the three-dimensional(3D)electrode based on macroporous electrically conducti,ve network(MECN).Silicon microchannel plates(SiMCP)can be formed by standard microelectromechanical system(MEMS)techniques.After electroless plating of nickel in vacuum,the macroporous electrically conductive network(MECN)is formed.Nickel-carbon alloy and nano-graphene are fabricated on the surface of MECN by hydrothermal carburization and subsequent annealing in Ar(named as NiC-MCP and NG-MCP,respectively).The electrochemical characteristics of MECN,NiC-MCP and NG-MCP are studied systematically in alkaline and neutral electrolytes.Experimental results show that the compact nickel-carbon surface layer protects the metal nickel layer,as a result of appropriate amount of carbon diffusion into the nickel layer.However,the nickel layer will expand excessively so as to decrease the stability when a large amount of carbon been introduced.The nano-graphene fabricated on the surface of nickel after annealing can improve the electrochemical properties especially the solution resistance,fast ions adsorption/desoption process due to the large surface area and high surface defective concentration,and the increasing stability in both alkalis and neutral electrolyte due to the protection of carbon element.Palladium nano-particles are electrodeposited on 3D MECN electrodes and hydrogen evolution performances of Pd/MECN,Pd/NiC-MCP and Pd/NG-MCP in alkaline electrolyte are studied systematically.At the current density of 10mA cm-2,the values of overpotential are about 96,48,and 47mV for Pd/MECN,Pd/NiC-MCP and Pd/NG-MCP,respectively,and the related Tafel slopes are about 185,121 and 112mV dec-1.Electrochemical analysis shows that Pd/NG-MCP has the best electrical conductivity,the most stable structure and the fastest reaction rate due to its smallest interface series resistance and charge transfer resistance.It could be the higher conductivity and structural stability of nanographene enables the 3D electrode exhibits the best electrocatalytic hydrogen evolution performance.