The influence of lowing the Schottky barrier on the reactive oxygen species formation in Ag@SrBi2Ta2O9 piezocatalyst under ball milling

Abstract

Loading noble metal nanoparticles on piezoelectric substrates to form the Schottky barrier is believed to be an effective way to promote charge separation and enhance the piezocatalytic performance. The presence of the exceeded Schottky barrier would influence the generation of reactive oxygen species (ROS). However, the detailed correlation between the Schottky barrier height and the type of ROS is not well established. Herein, a type of Aurivillius material, SrBi2Ta2O9 (SBTO) and its composite materials Ag loaded SBTO (Ag@SBTO), were synthesized for different bacteria inactivation and pollutants degradation under ball milling (BM). The results showed that Ag@SBTO3 (0.76 wt% Ag) could lead 7.46 log10 of E. coli K12 inactivation, which was 21.3 times higher than that of SBTO. And Ag@SBTO3 also can achieve about 98.05% of Oxytetracycline degradation, while SBTO showed a better efficiency in Minocycline Hydrochloride and Rhodamine B degradation, the degradation efficiency can reach up to 92.60% and 75.04%, respectively. The variety of catalytic efficiency can be attributed to the different Schottky barrier height and the reduced activation energy of the piezo system when they were subjected to BM effect, which ultimately changed the type of ROS. Our results confirmed that ·OH and ·O2– were the main ROS for SBTO and Ag@SBTO3 during the experiments, respectively, and BM lowering the Schottky barrier of Ag loading piezoelectric material was a facile strategy to generate different ROS for a wide range of applications in water pollution control and drinking water safety.