Surface charge transfer adjustment from designing thin-layer structure targeted O₂ adsorption and activation for deep NO oxidation on Bi₂MoO₆

Photocatalytic oxidation of nitrogen oxides (NO_x) is a promising technology for environmental protection and green sustainable development. However, its practical application remains limited due to inefficient activation of NO and O₂, stemming from inadequate structural design of photocatalysts. Herein, we developed a thin-layer two-dimensional (2D) material Bi₂MoO₆ (BMO) via cetyl trimethyl ammonium chloride (CTAC) addition in synthesis process, which effectively modulates the surface electronic structure, enhance the light absorption and activation of NO and O₂. This thin-layer Bi₂MoO₆ nanosheets achieved a NO oxidation efficiency of 45.3 ​%, which was about 5.5 times that of traditional bulk BMO (8.2 ​%). Additionally, it demonstrated superior selectivity for NO₂⁻/NO₃⁻ production (86.6 ​%) compared to bulk BMO (60.5 ​%) and significantly reduced the formation of toxic NO₂ byproducts (13.4 ​% vs. 39.5 ​%). Combining experimental characterizations and density functional theory (DFT) simulations, it demonstrated that the electron-hole pair separation could be promoted and targeted adsorption activation of O₂ can be enhanced to form superoxide radicals (•O₂⁻) and singlet oxygen (¹O₂) via the effect of surface charge transfer adjustment on the thin-layer structure of Bi₂MoO₆, which are key factors affecting the efficiency and selectivity of photocatalytic oxidation of NO. This work provides important insights into the formation of directed ROS and proposes a unique mechanism for selective NO oxidation.