Engineered Nanoscale Single-Metal-Oxides Catalytic Thin Films for High-Performance Water Oxidation

Surface assembling of nanoscale materials for electrocatalysis is imperative to progress water splitting. There is a dire need to develop cost-effective and easily accessible methods to make metal oxides, aiming to execute the oxygen evolution reaction (OER) at low overpotential and high stability for long-term activity. Thin-film metal oxides for water oxidation are prepared via aerosol-assisted chemical vapor deposition (AACVD) on simple substrates as shown here. Catalytic films (CFs) of CoO_x, NiO_x, CuO_x, and FeO_x are phase pure oxides, smooth, and of nanoparticulate type, and are highly crystalline. Water oxidation catalysis is initiated at low onset potentials and achieves 10 mA cm⁻² just at the potentials of 250–330 mV in 1.0 m KOH solution. All catalysts present impressive kinetics behavior for boosting OER activity, signifying their inherent potential for propelling water oxidation at lower energy demands. Excitingly, stable current densities remain sustained during prolonged period water catalysis. Promising behavior of the ultrafine CFs is attributed to the exploitation of the elegant synthetic strategy under controlled conditions to realize a high redox potential and cyclic M^2+/3+ couple activation with sustainable catalytic active sites. Nanoscale and porous features of the highly pure and crystalline films further promote the electrocatalytic process and remain intact even after long-term catalytic investigations.