One-step in-situ construction engineering of ZnO-Zn2SnO4 heterojunction for deeply photocatalytic oxidation of nitric oxide

A novel S-scheme ZnO-Zn2SnO4-based heterojunction with oxygen vacancies is in situ prepared. The synergistic effect of oxygen vacancies and S-scheme heterojunction not only generates rich active species but also activates small molecules, thereby greatly enhancing the deep oxidation efficiency of nitric oxide to nitrate under visible light irradiation. [Display omitted] The generation of hazardous intermediates during the process of photocatalytic nitric oxide (NO) oxidation presents a tough issue. Herein, a one-step microwave strategy was employed to introduce oxygen vacancies (OVs) into zinc oxide-zinc stannate (ZnO-Zn2SnO4) heterojunction, resulting in an improvement in the photocatalytic efficiency for NO removal. The construction ZnO-Zn2SnO4 heterojunction with the OVs (ZSO-3) owns a significant contribution towards highly efficient electron transfer efficiency (99.7%), which renders ZSO-3 to exert a deep oxidation of NO-to-nitrate (NO3−) rather than NO-to-nitrite (NO2−) or NO-to-nitrogen dioxide (NO2). Based on the solid supports of experimental and simulated calculations, it can be found that OVs play an irreplaceable role in activating small molecules such as NO and O2. Moreover, the enhanced adsorption capacity of small molecules, which guarantees the high yield of active radical due to the formation of S-scheme heterojunction. This work illuminates a novel viewpoint on one-step in-situ route to prepare Zn2SnO4-based heterojunction photocatalyst with deep oxidation ability of NO-to-NO3−.