Usage of Bi–O Channels and Internal Electric Field in Nanosheet/Hollow-Cube Heterojunction for Photocatalytic NO Purification

Catalytic purification of nitrogen oxide (NO_x) in the air environment is imperative due to increasingly strict emission regulations. The photocatalytic performance of NO_x removal often suffers from the mobility of carriers; therefore, encouraging the separation and transfer of photogenerated carriers by establishing an internal electric field (IEF) is an effective strategy. Herein, a simple reduction method successfully synthesized a series of nanosheet/hollow-cube BiOCl/ZnSn(OH)₆ (BOC/ZSH) photocatalysts. Material characterization and density-functional theory (DFT) calculations verified that the established internal electric field (IEF) at the BOC/ZSH interface can drive the directional migration of photogenerated electrons and further accelerate the transfer via the formation of Bi–O channels. The maximum NO removal efficiency of the optimized catalyst (BOC-15/ZSH) was 53.99%, which was 30.16 and 1.92 times higher than those of pure ZSH and BOC, respectively. Density functional theory (DFT) calculations revealed that BOC/ZSH had abundant active sites for strengthening the adsorption and activation of reactant molecules. Incorporated with in situ DRIFTS, the explored reaction pathways illustrated that heterojunctions could diminish the energy barrier for NO oxidation and assist in the oxidation of NO to nitrate (NO₃^–). This work lends insights into the fabrication and reaction pathway analyses of highly efficient photocatalysts for air pollution purification.