Investigation of the water-induced polar facet stabilization mechanism in ZnO nanoplates with 1H NMR spectroscopy

Abstract

ZnO with polar facets has been extensively studied in material sciences due to its wide applications. However, the stabilization mechanisms for polar surfaces in ZnO nanomaterials are still unclear. Here, we show that water can dissociate at Zn and O vacancies on the polar (0001)-Zn and (000)-O surfaces of ZnO nanoplates, respectively, producing H in the Zn vacancies and surface OH groups. Upon exposure to saturated water vapor, in addition to the peak arising from H in the Zn vacancies, the amount of surface OH species increases owing to water dissociation on both polar Zn- and O-terminated surfaces, resulting in significant electrostatic repulsion between these polar surfaces. This improves the dispersity of ZnO nanoplates and thus the stability of polar surfaces. These results are helpful for further understanding the polar facet-related stabilization mechanisms in oxide nanomaterials.