Influence of O₂ flow rate on the electrochemical hydrogen evolution reaction performance of Cu/Cu₂O/Grade stainless steel prepared by RF magnetron sputtering

The exploration of cost-effective and high-efficiency electrocatalysts for alkaline hydrogen evolution reaction (HER) is essential in tackling issues caused by carbon dioxide emissions. Cu₂O-based nanomaterials were evaluated as potential competitors to alter noble metal electrocatalysts for HER as a result of their low cost, abundance, and adjustable catalytic activities. In this study, Cu/Cu₂O nanostructures were deposited on commercial stainless steel (SS) via a vacuum deposition technique of radio frequency magnetron sputtering. The influence of various O₂ flow rates, including 5, 10, 15, and 20 sccm on the morphological structure and elemental ratio of Cu/O were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and Energy-dispersive X-ray spectroscopy (EDS). More importantly, the change in O₂ flow rates optimized HER efficiency and indicated that the optimal sample of Cu/Cu₂O/SS-10 provided better HER catalytic properties than that of the bare SS. In particular, this electrode required a low overpotential of 292 mV to achieve a current density of 10 mA cm⁻² and outstanding durability with 43200 s continuous hydrogen production. The high efficiency is attributed to the synergistic effect of the Cu₂O and Cu metal components and the high electrical conductivity of commercial SS, which benefits dissociative H₂O adsorption, adsorbed hydrogen recombination, and accelerating charge transfer in the catalytic process. This study could provide a straightforward and sustainable approach for preparing precious metal-free electrodes for alkaline water electrolysis.