CuO-modified WO₃ for stable photocatalytic NO oxidation: Overcoming photocorrosion and side reactions

Tungsten trioxide (WO₃) is an attractive photocatalyst for visible light applications, but its practical use is hindered by its instability due to the easy photoreduction of W⁶⁺ to W⁵⁺. To enhance its stability and efficiency, we developed a novel heterojunction by preparing nanoscale CuO on WO₃ nanosheets via a one-step calcination method. This CuO/WO₃ heterojunction effectively inhibits photocorrosion through an S-scheme charge transfer mechanism that redirects electrons from WO₃ to CuO. The optimized heterojunction achieved a significantly enhanced NO removal efficiency of 62%, which is approximately 2.2 times higher than that of pure WO₃ (27%), while also exhibiting excellent stability during cycling tests. The presence of CuO not only stabilized the WO₃ by diverting the hot electrons from the WO₃ surface, but also inhibited the production of toxic NO₂ on WO₃ through the singlet oxygen. This study demonstrates an effective strategy for constructing stable and efficient photocatalysts for atmospheric pollutant removal by optimizing interfacial charge transfer.