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

NaNbO 3 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, NaNbO 3 and Ag dots-modified NaNbO 3 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 C 0 = 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 NaNbO 3. The rate constant k of Ag dots-modified NaNbO 3 for piezo-photocatalytic degradation of RhB (C 0 = 5 mg/L) is increased to 0.16314 min−1. The optical and electrochemical activities of NaNbO 3 -0.75hAg are studied to reveal the role of Ag nanoparticles. The band gap of NaNbO 3 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, NaNbO 3 -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 NaNbO 3 and achieve outstanding piezo-photocatalysis for degradation of hazardous organic dyes in contaminated water. [ABSTRACT FROM AUTHOR]