One-pot solvothermal fabrication of S-scheme OVs-Bi2O3/Bi2SiO5 microsphere heterojunctions with enhanced photocatalytic performance toward decontamination of organic pollutants

Abstract Bi2O3/Bi2SiO5 microsphere heterojunctions self-assembled by nanoplatelets with rich oxygen vacancies (OVs) were fabricated through a mild one-step solvothermal approach. The existence of OVs was confirmed by XPS and low temperature electron spin resonance (ESR) technique. The crystal texture, morphology, and optical property of the 3D OVs-Bi2O3/Bi2SiO5 microsphere heterojunctions were analyzed by a series of characterization methods. The results reveal that OVs-Bi2O3/Bi2SiO5 heterojunctions were constructed and the diameter of microspheres is about 1 μm. The photocatalytic performance of OVs-Bi2O3/Bi2SiO5 composite microspheres was assessed using methyl orange (MO) and colorless phenol as model contaminant. The synergistic effect of Bi2O3 and Bi2SiO5 greatly enhances the removal rates of organic pollutants. O2– and h+ are predominant active free radicals in the photocatalytic process, supporting by ESR, nitroblue tetrazolium (NBT) and trapping experiments. The separation and transfer of the photoinduced charge pairs of OVs- Bi2O3/Bi2SiO5 heterojunctions follow a step-scheme mechanism. The step-scheme mechanism endows OVs-Bi2O3/Bi2SiO5 heterojunctions with higher photocatalytic performance than the bare Bi2SiO5.