Surface Engineering of Cu₂O Photocathodes via Facile Graphene Oxide Decoration for Improved Photoelectrochemical Water Splitting

Copper oxide (Cu₂O) has attracted significant interest as an efficient photocathode for photoelectrochemical (PEC) water splitting owing to its abundance, suitable band gap, and band-edge potential. Nevertheless, a high charge recombination rate restricts its practical photoconversion efficiency and reduces the PEC water-splitting performance. To address this challenge, we present the facile electrodeposition of graphene oxide (GO) on the Cu₂O photocathode surface. To determine the effect of varying GO weight percentages on PEC performance, varying amounts of GO were deposited on the Cu₂O photocathode surface. The optimally deposited GO-Cu₂O photocathode exhibited a photocurrent density of -0.39 to -1.20 mA/cm², which was three times that of a photocathode composed of pristine Cu₂O. The surface decoration of Cu₂O with GO reduced charge recombination and improved the PEC water-splitting performance. These composites can be utilized in strategies designed to address the challenges associated with low-efficiency Cu₂O photocathodes. The physicochemical properties of the prepared samples were comprehensively characterized by field-emission scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, Raman spectroscopy, UV-visible spectroscopy, and X-ray photoelectron spectroscopy. We believe that this research will pave the way for developing efficient Cu₂O-based photocathodes for PEC water splitting.