Effect of Electrolyte pH on Room-Temperature Photoelectrodeposition of Cu2O for Hydrogen Evolution Reaction

Cu₂O is a promising material for the hydrogen evolution reaction due to the favorable band gap. However, achieving a pure Cu₂O phase typically requires high deposition temperatures. To overcome this, electrolyte pH modification was employed to synthesize pure Cu₂O at room temperature. A key challenge in room-temperature electrodeposition is the slow deposition rate, which can be improved through photoelectrodeposition. This study explores the synthesis of pure Cu₂O via controlled pH photoelectrodeposition for applications of the hydrogen evolution reaction. The results demonstrate that Cu₂O films were successfully deposited in an alkaline electrolyte, with the best hydrogen evolution reaction catalytic performance observed at pH 8. This sample exhibited a low onset potential of 64 mV with respect to the standard reversible hydrogen electrode and a Tafel slope of 46 mV/dec. These findings provide the optimization of Cu₂O synthesis for hydrogen production.