Bifunctional electro-catalytic performances of NiMoO4-NRs@RGO nanocomposites for oxygen evolution and oxygen reduction reactions
Jahangeer Ahmed, Manawwer Alam, M.A. Majeed Khan, Saad M. Alshehri
Abstract
In present study, we report hydrothermal synthesis of reduced graphene oxide (RGO) supported NiMoO4-nanorods (NRs) nanocomposites (NiMoO4[email protected] nanocomposites) for electro-catalysis of water to oxygen evolution and reduction reactions (OER/ORR). The prepared nanocomposites were characterized by x-ray diffraction (XRD), Raman, Fourier transform infrared (FTIR), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), energy dispersive and x-ray photoelectron spectroscopy (XPS) techniques. The electrochemical performances of NiMoO4[email protected] nanocomposites were examined in 0.5 M KOH (alkaline electrolyte) using cyclic voltammetry (CV), linear sweep voltammetry (LSV), Tafel and chronoamperometry (CA) electrochemical techniques at room temperature. The onset over-potentials of NiMoO4[email protected] nanocomposite for ORR and OER were found to be of ~75 and ~185 mV, respectively, while the Tafel slopes for OER and ORR were observed to be ~54 and ~245 mV/dec respectively. The involved electrons (i.e. 4e−) in redox reactions were calculated using rotating disc electrode experiments. Based on admirable electro-catalytic performance of NiMoO4[email protected] nanocomposites with low energy loss, suggesting it as cost effective and efficient OER/ORR electro-catalysts compared to noble metal electro-catalysts.