Microcrystalline Bi2WO6 co-modified by oxygen vacancies and bismuth metal deposits for the efficient photocatalytic oxidation of nitric oxide

The efficient conversion of NO to NO 3 - and the generation of the by-product NO 2 are considered to be highly competitive reactions during the photocatalytic conversion of low concentrations of nitrogen oxides in the ambient atmosphere. However, achieving highly selective photocatalytic conversion of NO to NO 3 - remains a great challenge in current research. In this work, we successfully prepared a bismuth tungstate (BWO-40) with a microcrystalline domain, combines amorphous and crystalline structure, co-modified by oxygen vacancies (OVs) and bismuth (Bi) dual active sites. The composite photocatalyst exhibited a remarkable photocatalytic efficiency of 73.49%, reaching more than twice the efficiency of pure Bi 2 WO 6 , BWO-0 (26.66%), for NO conversion under visible light (λ ≥ 420 nm). The photocatalytic performance of BWO-40 significantly enhanced due to the synergistic effect between Bi and OVs as well as its microcrystalline structure. This not only facilitates the utilization of solar energy but also provides additional adsorption, thus improving the activation of reactant molecules while effectively suppressing the conversion of NO into the toxic by-product NO 2 (10.82 ppb). Furthermore, in-situ DRIFTS was used to investigate the adsorption and photocatalytic conversion pathways of NO. This work provides a feasible solution for achieving the highly selective conversion from low concentration of NO to NO 3 - of about 99% and effectively inhibiting the production of NO 2 .