Highly active PdxNi1−xO (0 ≤ x ≤ 0.5) nanocomposites for electrolytic water splitting in alkaline medium

Abstract

Abstract Nanocomposite electrocatalysts, having a general molecular formula of PdxNi1−xO (where 0 ≤ x ≤ 0.5), were synthesised employing a modified Pechini combustion method. The prepared electrocatalysts were subjected to physicochemical analyses such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The electrochemical characterisations of these catalysts were carried out employing cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and chronopotentiometry (CP). With nickel(II) oxide (NiO) being a well-known oxygen evolution electrocatalyst in alkaline medium, our synthesised NiO exhibited an overpotential of 262 mV (the lowest to date of all NiO electrocatalysts reported) at the benchmark current density of 10 mA.cm−2 in 0.1 M KOH. A palladium nanocomposite, however, in the form of Pd0.2Ni0.8O, delivered improved activity in that an overpotential of only 252 mV was required to accomplish 10 mA.cm−2. Charge transfer resistance at the electrode/electrolyte interface was calculated as being 14.25 Ω for the Pd0.2Ni0.8O electrocatalyst employing an EIS technique, which suggests fast kinetics. All electrocatalysts displayed good durability under the investigated conditions.