Band Gap Engineering and Lattice Distortion for Synergetic Tuning Optical Properties of NaNbO3 toward Enhanced Piezo-photocatalytic Activity

Piezo-photocatalytic efficiency is severely constrained by the wide band gap and bad piezoelectric properties. Herein, La(Mn0.5Ni0.5)O3 was successfully introduced into NaNbO3 lattices (referred to as 0LMN, 0.05LMN, 0.10LMN, and 0.15LMN) through a water-based sol–gel method. The piezo-photocatalytic degradation ratio for Rhodamine B (RhB) is enhanced from 59.7% (0LMN) to 89.7% (0.10LMN) within 100 min, and the kinetic rate constant (k) is increased from 0.009 to 0.022 min–1. The enhanced performance is attributed to (i) the narrowed band gap (from 3.40 to 2.84 eV), which is conducive to the generation of photogenerated electrons and holes, and (ii) the enhanced piezoelectric properties, which can strengthen the piezoelectric polarization, thereby accelerating the separation of the photogenerated electrons and holes. And we also found that the synergetic effect of photocatalysis and piezocatalysis was superior to that of photocatalysis and piezocatalysis alone. This study could provide new perspectives for the reasonable construction of an efficient catalyst in the piezo-photocatalytic field.