Regulating the Electronegativity Difference and Piezoelectric Strain of the S–Mo–S Structure via Introducing Mo Vacancies for Boosting Piezo-Photoelectric Activity

Recently, piezoelectric and photocatalytic processes have shown excellent synergistic effect addressing environmental remediation challenges. Herein, a nanoflower-like Mo vacancy-modulated MoS₂ (V_Mo-MoS₂) piezo-photocatalyst with different V_Mo densities has been successfully synthesized using a one-step hydrothermal method. The high V_Mo density (12%) facilitates the enhancement of the photocatalytic activity but compromises its structural stability, resulting in unsatisfactory piezoelectric activity. Among all V_Mo-MoS₂ piezo-photocatalysts, V_Mo-MoS₂ with 6% V_Mo density exhibits the highest piezo-photocurrent density (15.50 μA cm^-2), the largest potential difference (0.188 V), and the best carbamazepine (CBZ) degradation efficiency (95.81%) in only 10 min under light-ultrasound action, exhibiting a remarkable synergistic effect of the piezoelectric and photocatalytic processes. The synergistic performance originates from the simultaneous modulation of the charge distribution and the self-polarization capability of the S-Mo-S structure by V_Mo, as confirmed by the molecular theory calculations and finite-element simulation results. This work provides a defect engineering strategy for achieving the synergistic effect of the piezoelectric and photocatalytic processes, which opens a new research avenue for the design and application of the piezo-photocatalyst.