Exploration of a NiFeV multi-metal compositional space for the oxygen evolution reaction

Abstract

A sustainable future based on hydrogen fuel rests on the rapid advancement of non-precious metal catalysts for the oxygen evolution reaction (OER). We demonstrate the efficient utilisation in the analysis of a large compositional space of binary NiFe and ternary NiFeV alloys for OER using a combinatorial method. We fabricated a gradient library of these multi-metal alloys using physical vapor deposition and characterised them using high-throughput techniques. The electrocatalytic OER activity was studied using an automated electrochemical scanning droplet cell (SDC) set-up designed in our lab. From the overpotential (@10 mA cm⁻²) heatmaps of the libraries, the compositional regime of interest is funnelled down to 10–15% of Fe and 85–90% of Ni for the NiFe alloy and 1–3% V, 10–15% Fe, and 80–90% Ni for the NiFeV alloy with their overpotential values falling between 300–320 mV. Due to its oxidation state versatility, vanadium, is capable of inducing drastic changes in the electronic environment of the host element, boosting the OER activity. The effects of doping in the form of lattice distortions and electronic structure modifications have been investigated with XRD and XPS techniques. Our work shows the reliability and efficiency of the combinatorial approach in material discovery and applications, whilst also providing insights into the design of high performing OER catalysts.