The ClO· generation and chlorate suppression in photoelectrochemical reactive chlorine species systems on BiVO4 photoanodes

Photoelectrochemical generation of reactive chlorine species (PEC-RCS) is a promising approach for wastewater treatment . However, the inevitable byproduct of harmful oxychloride (such as ClO 3 − and ClO 4 − ) severely limits the practical applications of full-spectrum solar-driven PEC-RCS systems. Herein, we investigated three typical photoelectrodes including TiO 2 , WO 3 and BiVO 4 for PEC-RCS system and the formation of RCS and toxic oxychlorides. In BiVO 4 photoelectrochemical cell, the concentration of ClO 3 − was lower than 0.2 mg/L and the ClO 4 − was undetectable within 2 h of reaction. In contrast, the concentrations of ClO 3 − were 2.3 mg/L and 2.7 mg/L in the widely used WO 3 and TiO 2 PEC-RCS processes, respectively, which exceeded the health standard of 0.7 mg/L raised by the European Food Safety Authority (EFSA). We proposed that the valence band dependent photoelectrochemical properties of BiVO 4 photoelectrodes could lead to the restricted HO· radical production and the non-HO·-mediated RCS generation, which synergistically inhibited the ClO 3 − formation in the RCS activation process.