Piezo-assisted photoelectric catalysis degradation for dyes and antibiotics by Ag dots-modified NaNbO3 powders

NaNbO3 is explored as a potential candidate for catalysis due to its excellent piezoelectricity. However, its photocatalysis is significantly limited for the inherent characteristics of wide band gap. In this work, NaNbO3 and Ag dots-modified NaNbO3 micron-sized powders are prepared and applied in piezo-photocatalysis to explore the coupling effects. The results show that the piezocatalysis degradation efficiency of RhB solution (the initial concentration C0 = 5 mg/L) reaches 92.3% within 30 min, and the rate constant k is 0.0889 min−1. The efficiency of piezo-photocatalysis degradation reaches 92.7% in 25 min, and the rate constant k is 0.11 min−1 for NaNbO3. The rate constant k of Ag dots-modified NaNbO3 for piezo-photocatalytic degradation of RhB (C0 = 5 mg/L) is increased to 0.16314 min−1. The optical and electrochemical activities of NaNbO3-0.75hAg are studied to reveal the role of Ag nanoparticles. The band gap of NaNbO3 is 3.59 eV, which is decreased to 3.36 eV after the modification with Ag dots. The lower band gap means that e− in the valence band is more easily excited to shift the conduction band, which is beneficial to the photocatalytic reaction process. In addition, NaNbO3-0.75hAg has a higher photogenerated carrier density, a faster electron-hole pair separation and transfer rate, which are beneficial to the catalytic oxidation process. The work provides a useful means to decease the band gap of NaNbO3 and achieve outstanding piezo-photocatalysis for degradation of hazardous organic dyes in contaminated water.