Rationally designed core-shell of 2D-g-C3N4/Cu2O nanowires heterojunction photocathode for efficient photoelectrochemical water splitting

Abstract

Copper oxide (Cu2O) is a promising candidate as a high-performance photocathode due to its remarkable cost-to-efficiency ratio for photoelectrochemical (PEC) water splitting. However, fully exploiting the potential of planar Cu2O photocathodes for an efficient PEC performance remains a fundamental challenge owing to the poor light absorption and limited carrier diffusion length. To address these challenges, a graphitic carbon nitride (g-C3N4)/2D-Cu2O nanowires (NWs) with core-shell heterojunction photocathode has developed. The PEC water-splitting analysis reveals that the g-C3N4/Cu2O core-shell NWs photocathode boosted the photocurrent density from 0.83 mA/cm2 to 2.33 mA/cm2 at 0 VRHE (3-fold enhancement) compared with bare Cu2O. The formation of a g-C3N4 shell over the Cu2O core resulted in improved light harvesting as well as facile charge transport from the electrode to the electrolyte. Computational studies also revealed an impressive Gibbs free energy of 0.20 eV for the g-C3N4/Cu2O interface, highlighting its potential as an efficient PEC water-splitting device. These findings demonstrate that incorporating nanostructuring and overlayer strategies can remarkably enhance the PEC performance of Cu2O photocathodes, paving the way for more efficient and cost-effective water-splitting technologies.