Investigation on Photocatalytic Removal of NO under Visible Light over Cr-Doped ZnO Nanoparticles

[Image: see text] Removal of nitrogen oxide pollution has attracted much attention, and photocatalysis is considered as an effective method to treat polluted gas. Currently, modified semiconductors with approximate band gap are used as visible-light-driven photocatalysts. Herein, this is the first investigation of photocatalytic removal of NO under visible light over Cr-doped ZnO nanoparticles (Cr–ZnO NPs). Furthermore, the trapping species experiment and electron spin resonance measurement were conducted to identify the primary reactive factor of the photocatalytic reaction. In this study, Cr–ZnO NPs were synthesized by the sol–gel method with a narrow band gap, enhanced NO photocatalytic degradation performance, low NO(2) conversion yield, and high stability under visible light.