Anodically treated Ni/reduced graphene oxide electrodeposits as effective low-cost electrocatalysts for hydrogen evolution in alkaline water electrolysis

Abstract

Improvement of electrodes with earth-abundant materials is vital for a wider use of water splitting for hydrogen production. In this work, electrodeposits of Ni and Ni with reduced graphene oxide (Ni/rGO) were prepared by the galvanic square wave method. Ni/rGO had cauliflower-type morphology; its surface area was larger than that of Ni by over four times. XPS analysis showed more carbon and oxides on Ni/rGO. Electrochemical measurements in 1.0 M KOH revealed a new feature of Ni/rGO as compared with Ni, namely its greater anodic reactivity and stronger enhancement of hydrogen evolution reaction (HER) after anodic oxidation. The latter was explained by a refinement of the electrode surface by Ni being deposited through cathodic reduction of Ni oxides/hydroxides. Enhanced HER on Ni/rGO was explained by enlarged surface area and the formation of larger amounts of Ni oxides/hydroxides. Electrodeposition of Ni/rGO followed by voltammetric cycling might be a promising method for reactivation of cathodes for water electrolysis.