Oxygen vacancies and interfacial electric field co-induced photocatalytic performance of OVs-BiOI/α-Bi2O3 heterojunctions

Oxygen vacancies (OVs), as intrinsic defects and active sites in semiconductors, can trap electrons and activate O-2 under light irradiation, effectively restraining the recombination of photogenerated carriers. The interfacial electric field of heterojunctions can also guide the photoexcited carriers to separate purposefully. However, the relationship between OVs and interfacial electric field needs to be further unrevealed. In this contribution, OVs-BiOI/alpha-Bi2O3 p-n heterojunctions with excellent photocatalytic performance were successfully in-situ constructed by a solid-liquid reaction. The low-temperature electron paramagnetic resonance (EPR) confirms that this method can introduce abundant OVs into OVs-BiOI/alpha-Bi2O3 heterojunctions. Moreover, the theoretical calculations powerfully reveal that an interfacial electric field has been built in the interface of BiOI and alpha-Bi2O3. The photocatalytic efficiency of OVs-BiOI/alpha-Bi2O3 heterostructures was also tested by the destruction of tetracycline (TC) and methyl orange (MO) under simulated sunlight illumination. OVs-BiOI/alpha-Bi2O3 sample with 3% molar fraction of I/Bi has the best photocatalytic performance, deriving from higher specific surface area and the synergic effect between OVs and interfacial electric field. This work can shed light on elaborating the synergistic action of OVs and the interfacial electric field for improved photocatalytic performance.