Facile preparation of ultrathin Bi2MoO6 nanosheets for photocatalytic oxidation of toluene to benzaldehyde under visible light irradiation

Bi2MoO6 nanosheets different in thickness (~ 6 nm, ~ 15 nm and ~ 120 nm) were facilely prepared by hydrothermal and solvothermal methods. They were tested as photocatalysts for selective oxidation of toluene to benzaldehyde in the presence of O2 and under visible light irradiation. It was found that the photocatalytic activity is closely related to the thickness of Bi2MoO6 nanosheets. Apparently, thinner nanosheets could induce higher photocatalytic activity. Among them, the ultrathin Bi2MoO6 nanosheets (about 6 nm in thickness) which were prepared by a simple solvothermal method using MoO3 rods as precursor and ethylene glycol as solvent showed the highest activity (toluene conversion 12.7% and benzaldehyde production rate 778 μmol/g/h). The excellent activity is ascribed to the ultrathin sheet-like structure that facilitates efficient separation and transfer of charge carriers. Holes was found to be the main active species. Based on the controlled experiment and active species trapping results, a possible reaction mechanism was proposed.