Defect-driven piezocatalysis in zinc hydroxystannate: Role of oxygen vacancies and interfaces

Piezocatalysis is a promising technology that convert mechanical energy into chemical energy, offering sustainable solutions for environmental remediation. However, its development has been constrained by the assumption that effective piezocatalysis requires non-centrosymmetric materials. Herein, we demonstrate for the first time that zinc hydroxystannate (ZHS), a centrosymmetric material, exhibits efficient piezocatalytic activity for tetracycline (TC) degradation. Using a room-temperature self-template synthesis method, ZHS nanoparticles achieved a maximum TC degradation efficiency of 80 % within 180 min, comparable to classical piezoelectric material BaTiO 3 (BTO) under identical conditions. The ZHS-20 catalyst, optimized by NaOH concentration, also demonstrated excellent recyclability across multiple cycles. Comprehensive characterizations, including piezoelectric response force microscopy (PFM), second harmonic generation (SHG), and electron paramagnetic resonance (EPR) spectroscopy, revealed that oxygen vacancies are critical for piezocatalytic performance. Catalyst morphology and size were identified as key determinants of activity, surpassing the influence of surface area or oxygen vacancy concentration alone. Notably, while moderate oxygen vacancy concentrations improve carrier dynamics, excessive vacancies can act as charge traps, hindering the catalytic process. This study expands the scope of piezocatalytic materials to include centrosymmetric structures and provides insights into defect engineering, offering a scalable and sustainable strategy for environmental pollutant remediation.