Dual functional WO(3)/BiVO(4) heterostructures for efficient photoelectrochemical water splitting and glycerol degradation

Dual functional heterojunctions of tungsten oxide and bismuth vanadate (WO(3)/BiVO(4)) photoanodes are developed and their applications in photoelectrochemical (PEC) water splitting and mineralization of glycerol are demonstrated. The thin-film WO(3)/BiVO(4) photoelectrode was fabricated by a facile hydrothermal method. The morphology, chemical composition, crystalline structure, chemical state, and optical absorption properties of the WO(3)/BiVO(4) photoelectrodes were characterized systematically. The WO(3)/BiVO(4) photoelectrode exhibits a good distribution of elements and a well-crystalline monoclinic WO(3) and monoclinic scheelite BiVO(4). The light-absorption spectrum of the WO(3)/BiVO(4) photoelectrodes reveals a broad absorption band in the visible light region with a maximum absorption of around 520 nm. The dual functional WO(3)/BiVO(4) photoelectrodes achieved a high photocurrent density of 6.85 mA cm(−2), which is 2.8 times higher than that of the pristine WO(3) photoelectrode in the presence of a mixture of 0.5 M Na(2)SO(4) and 0.5 M glycerol electrolyte under AM 1.5 G (100 mW cm(−2)) illumination. The superior PEC performance of the WO(3)/BiVO(4) photoelectrode was attributed to the synergistic effects of the superior crystal structure, light absorption, and efficient charge separation. Simultaneously, glycerol plays an essential role in increasing the efficiency of hydrogen production by suppressing charge recombination in the water redox reaction. Moreover, the WO(3)/BiVO(4) photoelectrode shows the total organic carbon (TOC) removal efficiency of glycerol at about 82% at 120 min. Notably, the WO(3)/BiVO(4) photoelectrode can be a promising photoelectrode for simultaneous hydrogen production and mineralization of glycerol with a simple, economical, and environmentally friendly approach.