Scalable ambient conditions-based fabrication of flower-like bismuth vanadate (BiVO4) film incorporating defects aimed at visible-light-induced water-splitting application

Abstract

The scalable application of bismuth vanadate (BiVO4) in photoelectrochemical water splitting is restricted by its low charge separation efficiency and slow water oxidation kinetics. Here, modified BiVO4 photoanodes were fabricated at ambient conditions with polyethylene glycol (PEG) and potassium hydroxide (KOH) for improving the electron-hole generation rate and lowering the charge carrier recombination rate. Modification by PEG produced 3D flower-like BiVO4 microspheres, along with Bi5+, Bi(3−x)+, and V4+ species onto the PEG-BiVO4 surface, which were accompanied by oxygen vacancies (OVs) working in tandem with these species and acting as surface-active intermediates, thereby facilitating hole transfer to the electrolyte. Under visible light irradiation (100 mW/cm2), 3D flower-like PEG-BiVO4 microspheres produce the maximum photocurrent density of 5.75 mA/cm2 in water splitting at 1.23 V against a reverse hydrogen electrode (RHE). The superior photoelectrochemical performance of PEG-BiVO4 over its counterparts is attributed to the incorporation of 3D flower-like microspheres and band structure modulation by the O vacancies, Bi(3−x)+, Bi5+, and V4+ species. The synthesized PEG-BiVO4 is expected to attract attention as a scalable photocatalyst for oxidation of water because it is easy to synthesize at room temperature and it exhibits superb photocatalytic performance.