Photothermal effect induced humidity-resistant photocatalytic NO removal over dual-defects modified Bi/Bi4Ti3O12

Photocatalysis is appealing in removing trace NO, but its efficacy is often deteriorated by H 2 O, which is ubiquitous in environment, and how to resolve this issue and elucidate the underlying mechanisms at the molecular-level are challenging. Herein, we report a full-spectrum Bi/Bi 4 Ti 3 O 12 catalyst modified with Bi-O vacancy associates via a steam-assisted chemical reduction process. The optimized structure demonstrates NO removal efficiency of 75.5 %, four times over its counterpart, Bi 4 Ti 3 O 12 (37.9 %). Based on positron annihilation spectra and theoretical studies, the enhanced activity is induced by Bi-O vacancy associates, which not only optimizes the photogenerated carrier dynamical behaviors but lowers the energy barriers for photocatalytic oxidation of NO. Importantly, the photothermal activity of the optimal sample exhibited a decline from 76.7 % (0 % RH) to 71.2 % (100 % RH), whereas its photoactivity (20°C) demonstrated a more pronounced decrease, dropping from 60.1 % (0 % RH) to 41.2 % (100 % RH). Therefore, humidity-resistant performance over the optimal sample is attributed to photothermal effect induced by in-situ precipitated Bi and multiple defects. Furthermore, the results of adsorption and desorption behavior of H 2 O and in situ DRIFTS suggest the photothermal-assisted desorption of surface-bound H 2 O can suppress the interactions of H 2 O and stable bidentate nitrate ( bi -NO 3 ⁻) by hydrogen bonds to generate monodentate nitrate ( m -NO 3 ⁻), thereby hindering the photodecomposition of m -NO 3 ⁻ to NO/NO 2 . This work elucidates the significance of photothermal effect in developing efficient photocatalyst for atmospheric NO purification in humid conditions.