Facile synthesis of rGO/NiWO₄ hybrid electrocatalyst for enhanced oxygen evolution reaction in alkaline medium

Growing energy consumption and concerns regarding the effects of global warming are driving development of greener energy alternatives. Green hydrogen production and consumption are essential in modern energy conversion and storage. The progression of water splitting technologies for sustainable hydrogen production relies on the development of efficient and cost-effective electrocatalysts for the oxygen evolution reaction (OER). Here, we present nickel tungstate (NiWO₄) and reduced graphene oxide composited nickel tungstate (rGO/NiWO₄) synthesis via an easily processable successive ionic layer adsorption and reaction (SILAR) method, and its OER performance in an alkaline electrolyte. While NiWO₄ exhibited poor OER performance and stability, the incorporation of rGO significantly stabilized the composite electrode and extended its stability. The introduction of rGO reduced the charge transfer resistance and enhanced the surface area of the composite electrode compared to NiWO₄. As a result, rGO/NiWO₄ electrocatalyst exhibited a lower overpotential of 210 ± 10 mV at 50 mA cm^-2 and a Tafel slope of 60 ± 3 mV dec^-1, compared to NiWO₄ (260 ± 13 mV, 60 ± 3 mV dec^-1), showing enhanced catalytic performance. Additionally, the composite electrode demonstrated long term stability, over 50 h of continuous operation. These findings demonstrate rGO/NiWO₄ as a promising OER electrocatalyst for efficient water splitting.