Thickness-determined photocatalytic performance of bismuth tungstate nanosheets

Abstract

Bismuth tungstate (Bi₂WO₆) nanosheets with dominant exposed (010) facets and various thicknesses (H) and lateral sizes were hydrothermally synthesized via pH adjustment of precursor suspensions. As the pH increases from <1 to 8, the resultant nanosheets exhibit improved crystallinity and photoabsorption, decreased specific surface area, increased H, and decreased photoactivity in the degradation of rhodamine B (RhB), methylene blue (MB), and Eosin Y (EY) under visible light irradiation. The photoactivity of the Bi₂WO₆ sample obtained at pH < 1 is about 6, 100, and 25 times of that at pH 8 for RhB, MB, and EY degradation, respectively. The photoactivity enhancement is ascribed to reduction of the H. The photocatalytic efficiencies are inversely proportional to the reduction of H² when the nanosheets can be penetrated by incident light. This work reveals the structure–performance relationship of Bi₂WO₆ nanosheets and provides significant guidance for preparation of high efficient two-dimensional photocatalysts.