Nickel nanoparticles coated on the exfoliated graphene layer as an efficient and stable catalyst for oxygen reduction and hydrogen evolution in alkaline media

Abstract

In this work, we report simultaneous electrochemical exfoliation of graphite powder using SDS, anionic surfactant salts, and cyclic potential to prepare graphene on carbon paper. Then, Nickel is electro-reduced into graphene nanosheets on carbon paper and also on the bare carbon paper to use in alkaline media for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). Afterward, graphene and Ni-graphene are characterized using scanning electron microscopy, atomic force microscopy (AFM) and electrochemical technique. SEM images show the Cauliflower structure of Ni in the absence of graphene and nanoparticle shapeless in the presence of smooth graphene. The electrochemical results show an excellent catalytic activity of Ni-graphene/ carbon paper with an over potential of 90 mV (Versus Ag/AgCl), which is lower than the literature value for Ni in alkaline electrolyte for HER (120 mV dec−1). The effect of graphene support on the electrochemical impedance spectroscopy response, activation energy and HER activity of the samples are investigated carefully. Finally, we prepare a novel gas diffusion electrode by using Ni pasted on carbon paper for the ORR in fuel cells and compared it with standard Pt/C catalysts using linear sweep voltammetry.