Vibration catalysis of eco-friendly Na_0.5K_0.5NbO₃-based piezoelectric: An efficient phase boundary catalyst

Excellent vibration-electricity conversion in various piezoelectric materials is frequently restricted, thus hardly generates high mechanochemical potential eliciting by ferroelectric polarization for advanced catalysis processes. Herein, we propose a phase boundary in Li modified Na_0.5K_0.5NbO₃ (NKN) materials to improve the piezocatalytic activity, and the relationships among the composition, phase structure, electrochemical and catalytic performances were systematically investigated. An outstanding piezocatalytic performance was exhibited in the LNKN6 (6 mol % Li doped NKN) with coexistence of orthorhombic and tetragonal phases, and the piezocatalytic activity showed a superior repeatability and universal applicability for the degradation of organic pollutants. The reaction rate constant of the LNKN6 was up to 25.16 × 10⁻³ min⁻¹, which was 3.20 times than that of pristine NKN. The enhancement of piezocatalytic activity was confirmed by Landau-Ginsburg-Devonshire phenomenological theory and the transfer efficiency of force-generated electrons and holes, and then an appropriate mechanism of the ultrasonic vibration driven piezocatalysis was speculated. This work provides an alternative strategy to enhance the catalytic efficiency of piezocatalyst and the high activity of the NKN-based piezoelectrics has an important application for environmental remediation.