In-situ generation of oxygen vacancies and metallic bismuth from (BiO)2CO3 via N2-assisted thermal-treatment for efficient selective photocatalytic NO removal

In this study, a N-2-assisted thermal treatment method is proposed for in-situ formation of a series of oxygen vacancies (OVs)-rich Bi-0/Bi-based photocatalysts, including OVs-(BiO)(2)CO3, Bi-0/OVs-(BiO)(2)CO3, Bi-0/OVs(BiO)(2)CO3/beta-Bi2O3, Bi-0/OVs-beta-Bi2O3, Bi-0/OVs-beta-Bi2O3/alpha-Bi2O3 and Bi-0/alpha-Bi2O3. Mechanisms of in-situ formation of Bi-0 nanoparticles and generation of OVs in Bi-based photocatalysts are clarified. Apart from their contribution to the effective separation of photogenerated charge carriers and enhancement of light absorption, the effects of Bi-0 nanoparticles and OVs on selective photocatalytic oxidation of NO are also investigated. Among the synthesized Bi-based photocatalysts, Bi-0/OVs-(BiO)(2)CO3 shows the best photocatalytic activity and stability for photo-oxidative removal of NO. The systematic study of photocatalytic mechanism demonstrated that the Ohmic contact between OVs-(BiO)(2)CO3 and Bi-0 gradually promote the formation of center dot O-2(-) and center dot OH species. It is found that center dot O-2(-) plays an important role in the photocatalytic NO removal process, while center dot OH species can effectively inhibit the formation of NO2 during the NO removal process. The new approach demonstrated in this study can be applied for the in-situ formation of wide-solar-spectrum-responsive photocatalysts with efficient photo catalytic activity.

Automated summary

The study proposes a N-2-assisted thermal treatment method for in-situ formation of oxygen vacancies (OVs)-rich Bi-0/Bi-based photocatalysts, clarifying the mechanisms of Bi-0 nanoparticles synthesis and OVs generation. Among the synthesized photocatalysts, Bi-0/OVs-(BiO)2CO3 exhibits the best photocatalytic activity and stability for NO photo-oxidative removal, with the mechanism showing the importance of center dot O-2(-) and center dot OH species in the process.