In-situ construction of S-scheme (BiO)2CO3/TiO2 heterojunctions with enriched oxygen vacancies and enhanced photocatalytic performance

Solar energy is a sustainable, green, and clean energy source among all the energy sources. Photocatalytic degradation with the aid of solar energy has been the theme of wastewater treatment. In this work, (BiO)2CO3 (BOC) was synthesized on the surface of TiO2 in alkaline environment (pH = 10.0) using bismuth nitrate pentahydrate as the bismuth source and urea as the carbon source, thus S-scheme BOC/TiO2 heterojunctions were successfully in-situ constructed. The experimental consequences demonstrate that formation of BOC/TiO2 heterojunctions can induce rich surface OVs and generate a strong interfacial electric field between BOC and TiO2, which leads to the directional movement of photoinduced e−/h+ pairs. The effective segregation of photoexcited e−/h+ pairs can be attained by the collaborative action of surface OVs and the spatial electric field. After irradiation by a Xenon lamp for 60 min, the BOC/TiO2-3 sample accomplishes a decontamination efficiency of 98% and 97.5% for rhodamine B (RhB) and ciprofloxacin (CIP), respectively. Furthermore, the disintegration rate constant of RhB and CIP on the catalyst is 3.6-fold and 0.9-fold higher than that on the reference TiO2, respectively. According to the observations, segregation and migration of the carriers follows a S-scheme mechanism.