Insights into the electrode reaction process of nickel nanoparticles @reduced graphene oxide catalyst for ethanol oxidation in alkaline solution

Nickel nanoparticles uniformly anchored on reduced graphene oxide (Ni/RGO) nanosheets is successfully prepared by a facile wet-chemical method. It is found that many small Ni nanoparticles with the particle size of 4–8 nm are anchored on RGO, showing uniform dispersion. The Ni/RGO nanocomposite-modified glassy carbon electrode (GCE) (i.e., Ni/RGO/GCE) is investigated as an electrocatalyst for the ethanol oxidation reaction. Especially, the as-prepared Ni/RGO/GCE delivers excellent electrocatalytic performance in terms of the low peak potential value, the low reduction of its overvoltage, and satisfactory peak current density. The excellent electrocatalytic properties could be ascribed to the synergistic effect of Ni spherical nanoparticles and RGO nanosheets, which can lead to the high use ratio of Ni. It is proposed that the anodic peak that emerged in the potential negative-going sweep may be attributed to the oxidation of ethanol, which results from the high concentration of ethanol and an autocatalytic process at Ni/RGO/GCE.