Interface engineering of hollow CsPbBr3/Co3O4 p-n heterojunction with rich oxygen vacancy for highly enhanced photocatalytic CO2 reduction

Surface defect or p-n heterojunction is considered as an efficient strategy to fabricate intrinsic built-in electric field and facilitate the charge separation and transfer. Herein, a novel p-n heterojunction photocatalyst CsPbBr3/Co3O4 was constructed by a facile microwave-assisted method, in which CsPbBr3 QDs anchored on ZIF-67 derived Co3O4 nanocage can simultaneously introduce oxygen vacancies and strengthen the interfacial interaction. As a result, the as-prepared CsPbBr3/Co3O4 displays the satisfactory photocatalytic CO2 reduction performance without photosensitizer and sacrificial agent, and the optimal catalyst exhibits that the average electron consumption rate (Relectron) is 158.80 μmol‧g−1‧h−1, which is 12.41 times higher than that of pure CsPbBr3. Photoassisted Kelvin probe force microscopy (KPFM) and experimental characterizations exhibit the formation of strong built-in electric fields probably due to the rich oxygen vacancies in this p-n heterojunction. Besides, DFT calculations confirm that the charge transfer pathway, where the electrons are quickly migrated to the catalytic active sites through the formed Cs-O bonds, thus accelerating the charge separation. This work could establish an effective strategy for the rational design of p-n heterojunction to achieve high-performance CO2 conversion.