Enhancement of visible-light photocatalytic efficiency of BiOCl/Bi2O3 by surface modification with WO3

The visible-light photocatalytic efficiency of BiOCl/Bi2O3 composites was notably enhanced by covering their surfaces with monolayer of WO3. The photocatalytic activity of WO3/BiOCl/Bi2O3 in decomposing gaseous 2-propanol (IP) and aqueous 1,4-terephthalic acid (TPA) under visible-light irradiation (λ ≥ 420 nm) was maximized by introducing a 0.6 mol% of WO3 to BiOCl/Bi2O3, whereas further increases of WO3 sharply decreased its activity. This suggests that monolayer coverage of BiOCl/Bi2O3 with molecular WO3 optimizes photocatalytic activity, and therefore, that the role of WO3 is to improve the adsorption affinity of BiOCl/Bi2O3 toward OH−, H2O, and organic species. In the evolution of CO2 from IP, 0.6%WO3/BiOCl/Bi2O3 exhibited 2.7 times the photocatalytic efficiency of bare BiOCl/Bi2O3. Remarkably, its efficiency was estimated to be 1.7 times that of typical N-doped TiO2. Moreover, it was found that the surface coverage of WO3 greatly extended the chemical stability of BiOCl/Bi2O3 during photocatalytic reaction.

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► Visible-light photocatalytic activity of BiOCl/Bi2O3 was enhanced by WO3 coverage.
► In evolution of CO2 from 2-propanol, its activity was enhanced by 2.7 times.
► Photocatalytic activity of WO3/BiOCl/Bi2O3 was 1.7 times that of N-doped TiO2.
► Surface coverage of WO3 improved the chemical stability of BiOCl/Bi2O3.