The (0 0 2) exposing facets of WO3 boosting photocatalytic degradation of nitrobenzene

Photocatalysis is a potential technology for de-nitro of nitro-aromatic contaminants in wastewater. In this work, monoclinic WO3 powders and films with different exposing ratios of (0 0 2) facets were simultaneously synthesized via a hydrothermal method. Their structures and photoelectrochemical properties were investigated, and the WO3 powders were further used for nitrobenzene (NB) degradation. The NB removal efficiency increased with the increase of the exposing ratio of (0 0 2) facets of WO3, and a high efficiency of 91.65 % removal of NB was reached in 3 h reaction. Degradation mechanism was clarified with the investigation of the intermediates and final products. The (0 0 2) facets of WO3 play a crucial role in facilitating the charge carrier separation, producing more ∙OH radicals, and thus increasing the efficiency for NB degradation. Moreover, the reaction kinetics analysis revealed that the first phenolation step of NB is the slowest step in the tandem photocatalytic degradation of NB.