Energy and separation optimization of photogenerated charge in BiVO4 quantum dots by piezo-potential for efficient gaseous pollutant degradation

Despite the favorable absorption of BiVO4 to visible light, the photogenerated charges in BiVO4 are weak in catalysis and most of them were recombined before reaching the catalyst surface due to their low energy as well as poor separation and transfer capacities. In this work, we used piezo-potential generated in a strained ZnO nanorod to evaluate the photoelectrons energy and promote the charge separation and transfer in BiVO4 quantum dots. The BiVO4 quantum dots were decorated on the ZnO nanorod to construct a piezo-potential assisted photocatalyst. Our results indicated that the visible photodegradation rate of ZnO nanorod arrays with optimized BiVO4 quantum dots decoration was significantly improved in formaldehyde degrading under mechanical stimulation. The concentration of formaldehyde was decreased to similar to 0.2 ppm from 1 ppm in 1 h, which is similar to 2.5 times than that without piezo-potential assistance. The negative electric field generated in the ZnO nanorod when compressively strained was believed to have evaluated the conduction band of BiVO4 and thus the photoelectron energy. Moreover, the photoelectrons and holes were promptly driven to be transferred in the opposite direction before recombination by the piezoelectric field. These promotions lead to remarkably enhanced charge separation rate, which is directly responsible to the improved photocatalytic activity of the BiVO4 quantum dots.