Single-step strategy for the fabrication of GaON/ZnO nanoarchitectured photoanode their experimental and computational photoelectrochemical water splitting

Electrode materials efficiency and stability are two indispensable bottlenecks in solar-driven water splitting which impedes its large-scale productions. Here, we report the novel fabrication of GaON/ZnO nanoarchitecture over FTO substrate, as a conceivable substitute for efficient solar-driven photoelectrochemical (PEC) water splitting. The synthesis of nitrogen enriched photoactive GaON/ZnO is accomplished by the single-step hydrothermal method. The formation of GaON /ZnO is observed in field emission scanning electronic micrographs (FE-SEM), which suggested that the ZnO hexagonal nanorods (NRs) bulging out from the nanosheets of GaON carving nanoarchitecture morphology. X-Ray Photoelectron Spectroscopy (XPS) reveals the formation of Ga-N and Ga-O bonds in GaON/ZnO. The Tauc's plot shows red wavelength shift from 390 to 460 nm corresponds to bandgap 3.26–2.58 eV for ZnO/GaON. The observed photocurrent densities for GaON, ZnO and GaON/ZnO are ~ 0.2, ~ 0.4 and ~ 1.2 mA/cm², which reveals significant 6- and 3-folds increase for GaON/ZnO compared to pristine GaON and ZnO, respectively. The density functional theory (DFT) calculations for a model system consisting of Zn₃O₃ cluster on (111) surface of GaON shows strong water molecules absorption with probable water splitting reaction. Loading GaON surface with Zn₃O₃ nanoparticle further enhances the dissociative adsorption energy of water molecules. The experimental and theoretical findings provided a rational enhancement of water splitting process in GaON/ZnO nanoarchitecture.