Surface Engineering of Cu(2)O Photocathodes via Facile Graphene Oxide Decoration for Improved Photoelectrochemical Water Splitting

[Image: see text] Copper oxide (Cu(2)O) 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 Cu(2)O photocathode surface. To determine the effect of varying GO weight percentages on PEC performance, varying amounts of GO were deposited on the Cu(2)O photocathode surface. The optimally deposited GO–Cu(2)O photocathode exhibited a photocurrent density of −0.39 to −1.20 mA/cm(2), which was three times that of a photocathode composed of pristine Cu(2)O. The surface decoration of Cu(2)O 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 Cu(2)O 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 Cu(2)O-based photocathodes for PEC water splitting.