Efficient piezo-photocatalysis of Bi2O2(OH)NO3/BiOI heterojunction: Collaboration of piezoelectric polarization and interface electric field

Effective removal of recalcitrant pollutants is crucial for environmental protection. Tetracycline hydrochloride, as a representative recalcitrant organic pollutant, poses a potential threat to environmental integrity when present in aquatic ecosystems. Coupling piezoelectric polarization, capable of considerably promoting the photocharge separation, acts as a very prevalent and attractive strategy to improve the photocatalytic activity. In this study, an efficient piezo-photocatalytic system was developed in Bi2O2(OH)NO3/BiOI heterojunction by collaborating with interfacial electric field and vibration-induced piezoelectric polarization. The construction of type II heterojunction allows an interfacial electric field to propel the photogenerated electrons from BiOI to Bi2O2(OH)(NO3) under visible light irradiation. The introduction of vibration-induced piezoelectric polarization field strengthens the interfacial electric field, which further promote the separation and migration of photo-generated charges. Profiting from the above advantages, Bi2O2(OH)(NO3)/BiOI heterojunction exhibited a remarkable piezo-photocatalytic performance, achieving an over 80% degradation efficiency of tetracycline hydrochloride within 10 min, which far surpasses that under individual photocatalysis or ultrasound-induced piezocatalysis and also exceeds most of the previously reported piezo-photocatalysts. The combination of electron paramagnetic resonance, piezoresponse force microscopy, COMSOL simulation, and photoelectrochemical tests are conducted to probe the synergistically-catalytic mechanism. This work not only elucidates the comprehensive impact of interfacial electric field and piezoelectric polarization on charge separation, but also highlights the tremendous potential of piezo-photocatalysis for environmental remediation.