Nanostructured nickel ferrite embedded in reduced graphene oxide for electrocatalytic hydrogen evolution reaction

A non-noble metal electrocatalyst, nickel ferrite (NFO) having average particle size of 10.5 nm embedded onto the reduced graphene oxide (RGO) sheet, has been developed towards hydrogen evolution reaction (HER) in acidic medium. The phase purity and chemical coupling of NFO with RGO are established through X-ray diffraction, Raman and X-ray photoelectron spectroscopy studies. The NFO/RGO catalyst exhibits superior HER activity than bare NFO and other reported catalysts such as sulfides, carbides, phosphides, bimetals of molybdenum and iron-cobalt. A low onset overpotential of 5 mV (vs. RHE) with high cathodic current density, low Tafel slope of 58 mV dec(-1), low charge transfer resistance of 10.2 U, 99% Faradaic efficiency and turnover frequency of 0.48 s(-1) is obtained by virtue of mixed valent states of Fe, high specific surface area (109 m(2) g(-1)), excellent coupling between NFO and the RGO sheet creating oxygen vacancy. (C) 2018 Elsevier Ltd. All rights reserved.