Enhanced photoelectrochemical water splitting using nanostructured films: p-CuO sensitized with polyhedral n-Cu2O particles and CuS as photocathode

Abstract

The harnessing of solar energy to produce high-density energy carriers, such as hydrogen, through cost-effective technologies like photoelectrochemical cells (PECs), has emerged as a significant and promising effort. In this study, we employed p-CuO nanostructures, functionalized with polyhedral n-CuO and CuS particles, as a photocathode for water splitting. The fabrication process involved depositing copper onto FTO substrates via electrodeposition, followed by anodization to generate Cu(OH)₂ nanoneedles, which were subsequently transformed into CuO nanowires through annealing. Copper(I) oxide particles and CuS were deposited onto the CuO nanowires by electrodeposition and successive ionic layer adsorption and reaction (SILAR), respectively. The best CuO/Cu₂O/CuS film demonstrated a remarkable photocurrent of −2.74 mA cm⁻² at 0 V_RHE. In summary, the formation of a type II p–n heterojunction between CuO and Cu₂O facilitated improved charge separation, while the presence of CuS catalyzed the hydrogen evolution reaction (HER), highlighting the promising potential of this system for solar-driven hydrogen production.