Constructing multiple active sites of Bi2WO6 for efficient photocatalytic NO removal and NO2 inhibition

Abstract

Insufficient photocatalytic NO_x oxidation capacity will lead to excessive toxic by-products (NO₂), which still seriously restrict its practical application. Herein, the multiple active sites (Cl, Bi⁰ and OVs) modified Bi₂WO₆ has been established by in-situ synthesis method. The synergistic effect of multiple active sites greatly increased the photo-electric properties of the Bi₂WO₆, resulting in the boosting photocatalytic NO_x deep oxidation to nitrate. The visible light driven OVs-Bi@BWO-Cl catalyst exhibited a highest NO conversion efficiency (67.3 %) with extremely low NO₂ concentration (17.9 ppb). The synergism of structural regulation from the OVs with Cl-doping and surface plasmon resonance of Bi⁰ significantly enhanced light absorption and provided a fast charge transport channel, improving the separation efficiency of photo-generated carriers. The in-situ DRIFTS and density functional theory (DFT) results shown that the synergistic effect by multiple active sites could enhance the adsorption and activation of reactants to accelerate the processes of H₂O/O₂-to-ROS and decrease the energy barrier of NO removal to promote deep oxidation of NO-to-NO₃⁻. This work can provide ideas for the design and preparation of the catalyst for safe photocatalytic environment purification.