BiVO4/CuBi2O4 heterojunction photoanodes with enhanced charge separation for efficient photoelectrochemical water splitting

BiVO4/CuBi2O4 photoanodes were fabricated by depositing CuBi2O4 layers on top of BiVO4 layers while employing a solution-based deposition technique. Carrier separation and transfer are facilitated by the heterojunction that forms between BiVO4 and CuBi2O4, which significantly raises carrier density. Time-resolved photoluminescence (TRPL), UV–VIS absorption spectra, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were employed for the characterization of the photoelectrode. The heterojunction photoelectrode demonstrated enhanced photoelectrochemical activity in comparison to BiVO4 alone, with the maximum photocurrent density of 1.15 mA/cm2 at 1.23 V vs. RHE. The improvement is attributed to decreased recombination of photo-generated electrons and holes and improved charge separation and transport in the heterostructure. By the generation of heterojunctions, the current work offers a new avenue for the design and construction of photoanodes with high charge separation efficiencies. This may be useful for the further enhancement of PEC water-splitting performances.