An ultrafast carrier dynamics system from oxygen vacancies modified SnO2 QDs and Zn2SnO4 heterojunction for deeply photocatalytic oxidation of NO

Deeply photocatalytic oxidation of NO-to-NO 3 - holds great promise for alleviating NO x pollution. The major challenge of NO photo-oxidation is the highly in-situ generated NO 2 concentration, and the formation of unstable nitrate species causes desorption to release NO 2 . In this study, SnO 2 quantum dots and oxygen vacancies co-modified Zn 2 SnO 4 (ZSO-SnO 2 -OVs) were prepared by a one-step hydrothermal procedure, the NO photo-oxidation was investigated by a combination of solid experimental and theoretical support. Impressively, spectroscopic measurements indicate that fast carrier dynamics can be achieved due to the electron transfer efficiency of ZSO-SnO 2 -OVs reaching 99.99%, far outperforming the counterpart and previously reported photocatalysts. During NO oxidation, molecular NO/O 2 and H 2 O are efficiently adsorbed/activated around OVs and SnO 2 QDs, respectively. In-situ infrared measurements and calculated electron localized function disclose two main findings: (1) richly electrons enable NO promptly form NO - instead of toxic NO 2 or NO + ; (2) the generation of stable and undecomposed bidentate NO 3 - rather than bridging or monodentate one benefits the deep oxidation of NO via shifting reaction sites from O terminals for original ZSO to Sn ones for ZSO-SnO 2 -OVs. The synergistic action of SnO 2 QDs and OVs positively contributes to the NO oxidation performance enhancement (60.6%, 0.1 g of sample) and high selectivity of NO to NO 3 - (99.2%). Results from this study advance the mechanistic understanding of NO photooxidation and its selectivity to NO 3 - over photocatalysts.& COPY; 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.