Optimizing surface structure with Cu nanodots-decorated NiMoO₄ nanostructures to enhance electrocatalytic water splitting

The development of efficient, stable, and cost-effective electrocatalysts is crucial for advancing water-splitting technologies toward sustainable hydrogen production. This study introduces nickel molybdate nanorod-nanoflower (NiMoO₄ NRFs) blends decorated with copper nanodots (Cu NDs) on nickel foam (NF) as a dual electrocatalyst. Under alkaline conditions, the Cu NDs/NiMoO₄ NRFs/NF catalyst demonstrated impressive catalytic performance, requiring only −98 mV overpotential for hydrogen evolution reaction (HER) and 208 mV for oxygen evolution reaction (OER) at 10 mA cm⁻². Tafel slope analysis confirmed efficient kinetics, while impedance spectroscopy and capacitance measurements revealed enhanced charge transfer and abundant active sites. The catalyst demonstrated excellent stability for over 160 h, with improved performance after extended durability tests. It achieved a cell voltage of 1.57 V for overall water splitting at 10 mA cm⁻². Density functional theory (DFT) calculations revealed optimal Gibbs free energy for hydrogen adsorption (ΔG_*H = −0.03 eV) and suitable oxygen evolution adsorption energy (ΔG_*OOH − ΔG_*OH = 2.72 eV), along with a lower water splitting barrier (ΔG_b = 0.57 eV), supported by synergistic effects between Cu NDs and NiMoO₄. Structural characterization confirmed uniform Cu nanodot decoration, enhancing electron transfer. This work presents a scalable, cost-effective approach to high-performance electrocatalysts for sustainable energy.