Enhanced catalysis performances via synergy between the piezoelectric effect and optical excitation

Abstract

Piezoelectric materials have captured widespread attention in recent years, as they can effectively accelerate the separation of photo-generated charges and thus exhibit great potential in the photocatalytic decomposition of antibiotics. In this work, [001]-oriented NaNbO₃ (NNO) template crystals were used as substrates to increase the polarization and improve the ability of charge separation. The ZnO/NNO composite with the n–n heterojunction was obtained. The E_CB of NNO was −0.22 eV, which was higher than that of ZnO (−0.53 eV); electrons transferred from the conduction band of ZnO to that of NNO. Moreover, the conduction band energy (E_CB) of NNO was higher than the redox potential of ˙O₂⁻/O₂, which was conducive to the formation of ˙O₂⁻. The valence band energy (E_VB) of ZnO was 2.65 eV, which was lower than that of NNO (2.91 eV). Therefore, holes transferred from the valence band of NNO to that of ZnO. Meanwhile, the E_VB of ZnO was higher than the redox potential of ˙OH/OH⁻, which was conducive to the formation of ˙OH. With the synergy of piezoelectric and optical excitation, ZnO/NNO displayed a good degradation effect of oxytetracycline (OTC). 81% of the OTC was eliminated in just 30 minutes. Following four reaction cycles, the degradation efficiency of OTC by the ZnO/NNO composite exhibited only an 11% reduction, demonstrating the recyclability. It presented new application ideas for the [001]-oriented template crystals.