Synergistic defects and structural reconstruction in S-scheme Bi2MoO6-x-TiO2 heterojunction for enhancing piezo-photocatalytic degradation of gatifloxacin

Construction of heterojunction piezo-photocatalysts is a promising approach to improve catalytic performance for solving environmental pollution issues. However, the mechanism of the synergistic effect of defects and piezoelectric fields on the interface polarization, charge transfer, and active sites in heterojunctions still needs to be further explored. Here, oxygen vacancy-rich Bi2MoO6 (VBMO) and TiO2 (TO) were combined into an Sscheme heterojunction (VBMO-xTO) by hydrothermal method for piezo-photocatalytic degradation of gatifloxacin (GAT). Experimental and theoretical results confirm that oxygen vacancies induce the formation of Mo (VBMO)-O (TO) bonds at the interface, which in turn aggravates the internal reconstruction of the heterojunction. Simultaneously, the formed interface bonds strengthen the interface bonding force, improve its piezoelectric polarization, and acts as an interface electron bridge to promote charge transfer. In addition, under the action of ultrasound, the piezoelectric field generated by the compressive stress regulates the electron distribution of the heterojunction and enhances its adsorption performance. Benefiting from the synergistic reinforcement mechanism, VBMO-15TO exhibits excellent piezo-photocatalytic degradation of GAT, and the degradation rate is 92.5 % in only 6 min. This study provides a reference for understanding the effect of defects on the piezoelectric properties of heterojunctions.