Synthesis of surface sulfated BiWO with enhanced photocatalytic performance

Sulfated BiWO (SBiWO) was synthesized by an impregnation method to enhance the visible-light-driven photoactivities of BiWO (BiWO). The characterization results verified that sulfate anion mainly anchored on the catalyst surface greatly extended the visible-light-responsive range without destroying the crystal lattice. Moreover, the SBiWO-based photoactivities were evaluated with the removal of Malachite Green (MG) under UV-Vis irradiation emitted from two microwave-powered electrodeless discharge lamps (MPEDL−2) and under visible light (λ > 420 nm). The results demonstrated that the kinetic constant was increased 2.25 times, varying from 0.1478 (BiWO) to 0.3328 min−1 (SBiWO-1). Similar results were also obtained for the visible light-driven reaction. Furthermore, radical scavengers such as t-butanol restricted the visible-light induced degradation of MG over BiWO and SBiWO-1. This indicated that the sulfating process increased the generation of reactive oxygen species, which was further verified by molecular probe with salicylic acid. Thus, more blue-shifting at λ = 618 nm was observed over SBiWO. On the basis of the above results, the photocatalytic mechanism over the sulfated catalyst was also discussed.