Long-term stable piezocatalytic degradation of organic dyes using bulk LiNbO3 single-crystals

Abstract

Piezoelectric catalysis converts mechanical energy into chemical reactivity through electric fields generated by piezoelectric materials. Here, LiNbO₃ single-crystals are employed as a model piezocatalyst to elucidate the microscopic mechanism of ultrasonic-driven catalysis. The atomically ordered lattice ensures structural stability and enables precise defect-field correlation. Under ultrasonic excitation, cavitation-induced stress produces transient polarization fields that drive redox reactions without external bias. The ATR-FTIR spectra of methyl acrylate probe molecules reveal a carbonyl vibrational Stark shift, corresponding to an effective field of ∼6.6 × 10⁷ V m⁻¹. Experimental results demonstrate that single-crystal piezoelectric catalysts exhibit exceptional stability (>90% activity retention after 80 cycles), facile recovery due to their macroscopic monolithic morphology, and compatibility with integrated devices for scalable applications. These polarization fields facilitate interfacial charge separation and generate ˙OH and ˙O₂⁻ radicals responsible for dye degradation. This work demonstrates that LiNbO₃ single-crystals enable efficient, recyclable, and stable piezocatalysis and provides quantitative insights into the electromechanical–chemical coupling mechanism underlying ultrasonic piezocatalysis.