NiO/TMO (M = Cu, Co, Zn, Fe)/MXene Ternary Composites as Efficient Bifunctional Electrocatalysts for Oxygen Evolution and Reduction Reactions

MXene-based composites modified with NiO and secondary transition metal oxides (TMOs, M = Cu, Co, Zn, Fe) were systematically evaluated for their performance for the oxygen evolution (OER) and oxygen reduction (ORR) reactions in alkaline media. Uniform hydrothermal treatment of all materials (6 h, 180 °C), assisted with polyvinylpyrrolidone, resulted in the phase-pure formation of ternary structures, confirmed by morphological analysis. The introduction of TMOs markedly improved the intrinsic electrocatalytic activity compared to pristine MXene, highlighting the beneficial role of synergistic interactions within the composite structure. Among the studied materials, the NiO/γ-Fe 2 O 3 /MXene composite exhibited the most promising OER performance, while NiO/ZnO/MXene showed promising ORR activity, indicating that ZnO incorporation improves reaction kinetics and charge transfer. These findings suggest that NiO/TMO/MXene composites, composed of earth-abundant and cost-effective materials, represent a viable and sustainable alternative to noble-metal-based catalysts for efficient bifunctional oxygen electrocatalysis.