Preparation of CO2‐activated Porous Graphene for Enhancing the Electrochemical Hydrogen Storage Properties of Co9S8 Material

Abstract

AbstractIn this work, Co9S8 hydrogen storage material was synthesized by mechanical alloying. To improve the electrocatalytic activity and conductivity of Co9S8, a series of porous reduced graphene oxide (PRGO) materials were fabricated via a facile CO2 activation treatment of RGO at different processing times. The composites of Co9S8 doping with different amount of PRGO were manufactured through ball milling. During the electrochemical hydrogen storage test, the porous Co9S8+PRGO exhibited higher discharge capacity than Co9S8+NRGO and conventional Co9S8. Moreover, the CO2 activation time and additive amount of PRGO had significant impact on the electrochemical properties of Co9S8. Ultimately, the electrode of 6 wt.% PRGO‐2 modified Co9S8 attained the optimum discharge capacity of 653 mAh/g. The special porous structure and high specific surface area of porous graphene could provide more electrochemical active sites and facilitate the hydrogen diffusion. After PRGO modification, the cycling stability, high‐rate dischargeability (HRD) and kinetic properties of Co9S8 were also enhanced. It can be concluded that porous graphene possesses better effect than conventional graphene in improving the performance of hydrogen storage alloy.