High-performance BiVO4 photoanodes cocatalyzed with an ultrathin α-Fe2O3 layer for photoelectrochemical application

A high-performance bismuth vanadate (BiVO4) photoanode cocatalyzed with an ultrathin α-Fe2O3 layer was fabricated for photoelectrochemical water splitting and organic pollutant degradation. The ultrathin α-Fe2O3 layer, which can faciliate the holes transfer to the surface efficiently and thus avoid high charge recombination, was deposited on the surface of the BiVO4 photoanode using a spin-coating-based successive ionic layer adsorption and reaction (SILAR) method. The Fe2O3/BiVO4 photoanode was characterized by various techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy, while its photoelectrochemical activity was investigated by linear sweep voltammetry and incident photon-to-current conversion efficiency (IPCE). The optimized Fe2O3/BiVO4 photoanode demonstrated a photocurrent density of 1.63 mA cm−2 at 1.23 V vs. a reversible hydrogen electrode (RHE) in a 0.1 M KH2PO4 (pH 7) electrolyte under simulated AM1.5G solar light and an IPCE value above 27% at 400 nm, which were 2.14 times and triple that of pristine BiVO4 photoanode, respectively. Furthermore, the Fe2O3/BiVO4 photoanode showed excellent stability and efficiency for the photoelectrocatalytic degradation of phenol compared with the bare BiVO4 photoanode. The chemical oxygen demand (COD) removal ratio increased from 42.3% to 68.89% after 120 min, which could be attributed to the efficient separation and transfer of the photogenerated carriers.