Ultrahigh piezocatalytic activity in (K, Na)NbO3 based materials

Abstract

Achieving outstanding piezoelectric catalytic performance is of significant importance in the fields of environmental remediation and energy conversion. Currently, the primary strategies for modulating piezoelectric catalytic performance focus on composition optimization and microstructural morphology design, yet the performance metrics (typically characterized by the piezoelectric catalytic constant k) generally remain relatively low (k ∼ 100 ×10⁻³ min⁻¹). In this work, we propose a multiscale strategy involving synergistic regulation of phase engineering, atomic-scale polarization heterogeneity, and grain morphology. In an Sb-doped 0.958(K,Na)NbO₃-0.04(Bi,Na)ZrO₃-0.002BiFeO₃ (i.e.,0.958 K_0.45Na_0.55Nb_0.96Sb_0.04O₃-0.04Bi_0.5K_0.5ZrO₃-0.002BiFeO₃)(Sb-doped KNN-BKZ-BFO) system, we successfully achieved an ultrahigh piezoelectric coefficient (d₃₃ ∼ 610 pC/N), high remnant polarization (P_r ∼ 23 μC/cm²), and moderate dielectric constant (ε_r ∼ 3000). In the degradation of Rhodamine B dye, this material exhibited exceptional piezoelectric catalytic activity (k = 283.16 ×10⁻³ min⁻¹), surpassing most reported lead-free piezoelectric catalysts. Multiscale structural characterization confirmed that the remarkable performance enhancement stems from two key factors: (1) the Sb doping-induced room-temperature R-O-T multiphase coexistence structure and enhanced atomic-scale polarization rotation, and (2) the larger grain size achieved through thermal management, which synergistically improves the piezoelectric coefficient and remnant polarization, thereby facilitating high piezoelectric potential and catalytic performance. This strategy is expected to provide important insights for developing next-generation high-performance lead-free piezoelectric catalysts.