Boosting bulk photocharge separation and transfer in heterojunctions for antibiotics removal: Enhanced internal electric field and interfacial electric field

The electric fields created by semiconductor heterojunctions often only separated photogenerated charges at component interface, not sufficiently inhibiting carriers' recombination in their bulk phases. Herein, we introduced the enhanced bulk internal electric field into BixOyIz/g-C3N4 heterojunction, constructing a dual electric field structure through in-situ precipitation and calcination to boost photocharge separation and transfer at both the interface and the bulk. The interfacial electric field created by heterojunction boosted the photocharge separation, and the enhanced internal electric field resulting from iodine reduction improved the bulk charge dynamics of BixOyIz. The dual electric field endowed BixOyIz/g-C3N4 with high photocatalytic activity and broad application potential. Specifically, the photocatalytic reaction rate constants of BixOyIz/g-C3N4 calcined at 460 degrees C for tetracycline removal reached 0.024 min(-1), which was 3.42 times higher than that of BiOI/g-C3N4. The electron paramagnetic resonance (EPR) and scavenging experiments proved that center dot O-2(-) was the predominant active species in oxidizing tetracycline. The experiments on simulated real water showed that BixOyIz/g-C3N4 has a broad range of pH applicability, strong resistance to anionic interference, and good cycling performance. This work provided new insights for inhibiting bulk phase photocharge recombination of individual components in heterojunctions.