Constructing the relationship between microstructure and piezocatalysis in (K, Na)NbO3 lead-free piezocatalyst

Piezocatalysis converts mechanical vibration into chemical energy and holds great potential for wastewater treatment and biomedical applications. Although the influence of microstructure on piezocatalysis is well recognized, its relationship has been rarely investigated in potassium sodium niobate ((K, Na)NbO3, KNN), an emerging lead-free and eco-friendly piezocatalyst. In this study, we modified the synthesis conditions of (K0.48Na0.52)NbO3-0.3 %Fe2O3 (KNN-Fe) material to produce KNN-Fe piezocatalysts with different microstructure characteristics. We then examined the relationship between microstructure and piezocatalysis by assessing the degradation of Rhodamine B (RhB) and methyl orange (MO) dyes. The KNN-Fe piezocatalyst with an 8 h-sand-ground shows the reaction rate constant (k) values of 79 × 10−3 min−1 and 27.12 × 10−3 min−1 for the degradation of RhB and MO, respectively. These values are 16 % and 303 % higher than those of the sand-ground-0 h sample. The enhanced piezocatalysis of the sand-ground-8 h sample stems from the increased specific surface area and oxygen vacancies, enhanced separation of electron-hole pairs, and higher carrier concentration. This study not only elucidates the relationship between microstructure and piezocatalysis in KNN materials but also suggests a potential approach for enhancing piezocatalytic activity.