Enhanced trimethoxypyrimidine degradation by piezophotocatalysis of BaTiO3/Ag3PO4 using mechanical vibration and visible light simultaneously

Enhanced degradation of trimethoxypyrimidine (TMP) was achieved by the piezophotocatalysis of barium titanate/silver orthophosphate (BaTiO3/Ag3PO4) using both mechanical and light energy. The hybrid BaTiO3/Ag3PO4 was synthesized by a facile co-precipitation method with an optimized mass ratio of BaTiO3 to Ag3PO4 of 1:3. The TMP removal efficiency of the piezophotocatalysis of BaTiO3/Ag3PO4 reached 85% within 30 min, which was 56% higher than that of the piezocatalyst, and 17% higher than that of the photocatalyst. The rate constant for the piezophotocatalysis of BaTiO3/Ag3PO4 was 4.5 times that of piezocatalysis, 1.6 times that of photocatalysis, and 1.2 times that of the sum of the piezo and photocatalysis. At the same time, the current density under both visible light and ultrasound was also enhanced when compared with that of the system subject to visible light or ultrasonic vibration individually. Holes were verified to be the dominant reactive species of piezophotocatalysis through scavenger testing and reactive species determination. This indicated that the piezoelectric field from the vibration-driven BaTiO3 promoted the separation of the photo-generated electron-hole of Ag3PO4, thereby producing more holes to degrade TMP. The TMP degradation pathways were proposed according to the structure of the parent compound and the mass-to-charge ratio of the by-products in the LCMS analysis. The results provided a promising strategy for enhancing the photo-generated electron-hole separation and for capturing mechanical and visible energy from the environment.