Harvesting the Vibration Energy of CdS for High-Efficient Piezo-Photocatalysis Removal of U(Ⅵ): Roles of Shape Dependent and Piezoelectric Polarization

Piezo-photocatalysis could coalesce the advantages of mechanical vibration and solar energy perfectly to achieve high-efficiency catalytic activity. Herein, the quintessential piezoelectric material CdS nanowires with different aspect ratios are precisely constructed and applied for piezo-photocatalytic reduction of U(Ⅵ) for the first time. The ultrasonic (60 kHz, 100 W) induces piezoelectric potential to generate a 0.57 eV A⁻¹ electric field, which is added to the direction of CdS (010) as a driving force to efficiently separate photogenerated charges. The alliance between piezoelectric effect and photocatalytic activity endows CdS NW-3 with the fastest piezo-photocatalytic rate under ultrasonic vibration and 5 W LED irradiation, and the relevant rate constant (0.042 min⁻¹) is about 12 and 53.8 times than that of LED and ultrasonication. More importantly, 93.74% of U(Ⅵ) could be removed from natural uranium mine wastewater. Therefore, this piezo-photocatalysis system that reduces U(Ⅵ) to easily separable (UO₂)O₂·2H₂O(s) provides valuable input for disposal applications of radioactive wastewater and broadens the horizons of nuclear energy utilization toward the advancement of carbon neutrality.