The CoMoO₄ Nanorods/Graphene Composite Base On Macroporous Electrically Conductive Network For Supercapacitor And Hydrogen Evolution Reaction

The three-dimensional silicon microchannel plates?Si-MCPs?of porous structured can be prepared by the microelectromechanical system?MEMS?techniques.Because of the high aspect ratio?square pore size of 5?m×5?m,the depth is 220?m?and large surface area,Si-MCPs have good prospect to be an excellent substrate of electrode in the supercapacitor and hydrogen evolution reaction application.In order to improve the conductivity of the silicon microchannel plate,we grown an uniform nickel particle layer on the surface and microchannel of the Si-MCPs by electroless plating to obtain the macroporous electrically conductive network?MECN?.We used the MECN to be substrates,through a simple hydrothermal method and annealing in the argon to synthesis multilayer nanographene on the surface and hole of MECN?nanographene/MECN?.The introduction of the nanographene not only improves the electrical conductivity of electrode,but also provide more active sites to the electrode.By the simple hydrothermal and annealing,the CoMoO₄ nanorods with ordered structures were grown on the nanographene/MECN electrode and finally obtained the CoMoO₄/nanographene/MECN composite electrode.Through a variety of characterization and electrochemical test methods,the performance of the CoMoO₄/nanographene/MECN composite electrode in supercapacitor and hydrogen evolution reaction were explored.We have obtained that the CoMoO₄/nanographene/MECN composite electrode has a capacity of 684 F g^-1(6.84 F cm^-2)at current density of 1 A g^-1(10 mA cm^-2).Moreover,it has a good cycle stability,at the current density of 20 mA cm^-2,after 5000 cycles can still reach 86.4%of the initial capacity.The asymmetric supercapacitor composed of CoMoO₄/nanographene/MECN||AC/Ni-foam also have good capacitance characteristic,at the power density of 675.5?W cm^-2(33.78 mW cm^-3),energy density can reach 112.4?W h cm^-2(5.62 mW h cm^-3).After 5000 cycles,the capacity can still maintain 74.4%of the initial capacity.At the same time,we analysed the performance of CoMoO₄/nanographene/MECN composite electrode in the hydrogen evolution reaction.The overpotential of CoMoO₄/nanographene/MECN composite electrode₁₀=79.5mV at the current density of 10 mA cm^-2,and the tafel slope is 74 mV/dec,showing a good performance of hydrogen evolution reaction.After 5000 cycle CV tests at the scanning speed of 60 mV s^-1,the overpotential₁₀ of CoMoO₄/nanographene/MECN composite electrode only increased to 82 mV,showing a good cycle stability.