Sulfur-induced electron migration in thin-layered Bi2MoO6 triggers 1O2-dominated pathway for selective NO photoconversion

The environmental benefits of photocatalytic oxidation of nitrogen oxides (NO x ) critically depend on the selective conversion of NO to nitrate (NO 3 − ) rather than to toxic by-products like nitrogen dioxide (NO 2 ). However, conventional photocatalysts suffer from low carrier separation efficiency and insufficient generation of reactive oxygen species (ROS), resulting in low selectivity of NO 3 − and high levels of toxic by-products. To address this issue, this study incorporates sulfur into thin-layer Bi 2 MoO 6 to induce charge rearrangement, precisely regulate electron transfer pathways, and promote the generation of targeted ROS. Experimental results showed that the S-doping Bi 2 MoO 6 catalyst exhibited exceptional photocatalytic performance, achieving 71.2 % NO removal efficiency, 93.1 % NO 3 − selectivity, a low NO₂ by-product concentration (43.2 ppb), and good cycle stability. Combining electron spin resonance (ESR) and ROS quenching experiments, the S-doping mediated electron transfer mechanism and ROS dominated by 1 O 2 were revealed, and the synergistic effect between surface electron enrichment and O 2 activation was elucidated. Theoretical calculation indicated that S 2− could act as electron capture centers to promote directional transfer of electrons by the strengthen Bi S covalent interaction, achieving high chemical adsorption activation of O 2 to trigger 1 O 2 generation. This research provides a novel strategy for steering ROS generation through directed electron transfer engineering, advancing the development of efficient and eco-friendly photocatalysts for air pollution remediation.