Br−/Bi0 synergistic engineering of Bi2WO6-x boosts visible-light NO deep oxidation via promoting NO2−-to-NO3− step with near-zero NO2 emission

Herein, Br − and Bi 0 co-modified Bi 2 WO 6-x nanosheets were synthesized for efficient photocatalytic NO removal. Plasmonic metallic Bi 0 markedly enhanced visible light absorption, and the Br − -Bi 0 synergistic interaction facilitated efficient separation and migration of photogenerated carriers. Consequently, the optimal catalyst achieved a maximum visible-light-driven NO removal efficiency of 53.1% with near-zero toxic NO 2 accumulation, significantly outperforming pristine Bi 2 WO 6-x (4.6%). Quenching experiments reveal that NO activation and oxidation are dominated by photogenerated e − and •O 2 − radicals, while photogenerated h + drives the subsequent deep oxidation of NO 2 . In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) combined with density functional theory (DFT) calculations confirm the coexistence of direct (NO → NO −  → NO 3 − ) and indirect (NO → NO 2 −  → NO 3 − ) NO deep oxidation pathways. The Br − -Bi 0 synergy promotes the NO 2 − -to-NO 3 − step, effectively suppressing toxic NO 2 accumulation. This work provides mechanistic insights into the design of advanced photocatalysts for safe and efficient atmospheric pollutant purification.