Enhanced piezo-phototronic effect of ZnO nanorod arrays for harvesting low mechanical energy

In this paper, ZnO photocatalytic activity was enhanced by a built-in piezoelectric field due to the piezoelectric effect of ZnO nanorods (NRs). A simple, practical, and self-powered device was designed to simulate and harvest the very low energy of ocean waves. By testing the degradation efficiency of ZnO for different polar dyes (methyl orange, natural red and rhodamine B), the role of the dynamic built-in electric field in the photocatalytic process was illustrated. The changing piezoelectric field acts as a “photo-induced carrier storage” in that the photo-induced carriers would be separated, stored, and released on the ZnO NR surfaces incessantly, improving the separation efficiency of photo-induced carriers in the ZnO NR array. The intensity and frequency of the built-in oscillating piezoelectric field are proportional to the ZnO NR array photocatalytic efficiency. The sustainable piezo-photocatalytic performance of the ZnO NR arrays should promote further applications of ZnO photocatalyst in pollution degradation.