Correlation between Photocorrosion of ZnO and Lattice Relaxation Induced by Its Surface Vacancies

ZnO samples with different surface vacancy defects in nature were successfully synthesized via a hydrothermal method, and the correlation between the surface defects and photocorrosion was investigated by applying a photoelectric response testing system. Here, we report on findings showing that the defects of the oxygen vacancies (V(o)s) induce a local electric field attributable to an inward lattice relaxation, resulting in weakness and cleavage of the Zn-O bond (i.e., photocorrosion) around the V(o)s. In contrast, the zinc vacancies (V(zn)s) inhibit photocorrosion by forming an outward lattice relaxation. These results suggest that the photocorrosion of ZnO is related to the lattice relaxation induced by the defects in ZnO. Furthermore, we have proved that the H-2, O-2, and H2O molecules adsorbed operate as an electron acceptor to receive the excess electrons localized around V(o)s. These processes were found to construct an electron-transfer channel to induce a reduction or elimination of the local electric field around V(o)s, leading to the inhibition of photocorrosion. Thus, the present results open new insights into the understanding of the photocatalytic activity as well as photocorrosion of the ZnO crystal surface and their correlation.

Automated summary

The study reveals that photocorrosion of ZnO is related to surface defects, with oxygen vacancies causing corrosion and zinc vacancies inhibiting it. Additionally, molecules like H-2, O-2, and H2O can act as electron acceptors to reduce the local electric field and prevent photocorrosion.