Oxygen vacancy engineering of Bi2O2CO3 hierarchical microspheres for enhanced adsorption of Cd2+ ions and photocatalytic degradation of Rodamine B

Oxygen vacancies (OVs) can adjust surface and electronic structures of materials and behave as active sites, extend spectral responsive range, and promote the transfer and separation of photogenerated carriers. Therefore surface properties and photocatalytic activities of materials can be enhanced via the incorporation of OVs. However, the influences of OV concentration inside a material on its adsorption ability for heavy metal ions associated with surface and photocatalytic activities under different atmospheres are still unexplored. In this work, in order to obtain highly efficient adsorbents and photocatalysts, rose-like Bi2O2CO3 hierarchical microspheres with rich OVs (Bi2O2CO3-ROVs) and deficient OVs (Bi2O2CO3-DOVs) were synthesized through a facile hydrothermal route and H2O2 oxidation treatment, respectively. Bi2O2CO3-ROVs hierarchical microspheres showed 2.4-times larger adsorption capacity than Bi2O2CO3-DOVs counterparts. The former also showed significantly enhanced photocatalytic activity for Rodamine B (RhB) degradation in aqueous solution under air, N-2, and Ar atmospheres than the latter, especially under anaerobic conditions. Our work demonstrated that OV engineering could provide a new strategy for enhancing adsorption capability and photocatalytic activity under both aerobic and anaerobic conditions of materials.