Carbon coated Cu ₂ O/CuO nanowire photocathodes for enhanced photoelectrochemical water splitting performance

Abstract

We herein report the fabrication of mixed oxide Cu2O/CuO nanowire electrodes through the anodisation of Cu-mesh. These synthesised electrodes are then coated with a protective carbon layer to enhance hydrogen production via photoelectrochemical (PEC) water splitting. Our study addressed Cu2O/CuO nanowire surface modification via anodisation voltage adjustment and analyzed annealing effects on carbon-coated electrodes under controlled temperatures in a nitrogen environment. Optimisation at 5V anodisation potential yielded enhanced photocurrents, with the Cu2O/CuO mixed phase proving crucial for improved PEC activity. XRD, SEM and TEM analyses were conducted to evaluate the structural and morphological characterisation of the synthesised samples. A thin carbon coated sample annealed at 550 °C enhances the photoelectrochemical efficacy of Cu2O nanowires, obtaining a peak photocurrent density of ∼4 mA cm−2 at 0 V (vs. RHE). In contrast, as prepared pristine optimised Cu2O/CuO nanostructured electrodes deliver a photocurrent density of ∼ 2 mA cm−2 at 0 V (vs. RHE) under AM 1.5G light solar irradiation with an intensity of 100 mWcm-2. The Mott–Schottky analysis exhibits p-type semiconducting nature of carbon coated Cu2O/CuO electrodes. The photocurrent stability test alsoconfirms that carbon coated Cu2O/CuO electrodes are one of the best candidates for improving the photoelectrochemical water splitting reaction.