2D–2D WO3–Bi2WO6 photocatalyst with an S-scheme heterojunction for highly efficient Cr(vi) reduction

Abstract

A two-dimensional (2D)–2D WO₃–Bi₂WO₆ photocatalyst is developed by using a hydrothermal method. Ultrathin Bi₂WO₆ nanosheets are grown on the surface of WO₃ nanoplates by crystal-oriented epitaxy. The 2D–2D WO₃–Bi₂WO₆ heterostructures display outstanding photocatalytic activity in reducing high concentrations of Cr(VI), as a 200 mg L⁻¹ Cr(VI) solution can be totally degraded within 40 min. The enhanced photocatalytic performance is ascribed to the synergistic effect of the 2D–2D heterostructure between Bi₂WO₆ and WO₃, which provides more active sites and large surface areas, and the S-scheme transfer behavior of photogenerated electrons and holes boosts the interfacial charge separation, and retains the optimum redox ability of photo-induced charge carriers. Active radical scavenging measurements verify that h⁺ and ˙O₂⁻ are the main active species during the photocatalysis. These findings would inspire new opportunities for engineering emerging heterostructures with a high photocatalytic performance.