Controllable Tuning Various Ratios of ZnO Polar Facets by Crystal Seed-Assisted Growth and Their Photocatalytic Activity

In this paper, Bi2WO6 was, for the first time, utilized as crystal seeds to fine control the ratio of ZnO polar facets under a mild condition. The structure and photocatalytic properties of the ZnO were investigated by powder X-ray diffraction, Raman scattering measurements, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, total organic C analyzer, Brunauer-Emmett-Teller surface areas, and electrochemical workstation. It was found that ZnO architectures were gradually changed from nanorods to nanosheets after adding a certain amount of Bi2WO6 crystal seeds, which led to the change of the ratio of ZnO polar facets. The formation mechanism for this ZnO and the effect of ZnO polar facets on the photocatalytic activity are explored in detail. We find that the nucleation and growth rates of ZnO are controlled by adjusting the quantity of the crystal seeds. Besides, photocatalytic activity of the samples tuned by Bi2WO6 crystal seeds was compared. The ratio of ZnO polar facets is the main factor influencing the photocatalytic activity. The results clearly demonstrate that the sample with a higher proportion of Zn-terminated (0001) and O-terminated (000 (1) over bar) polar facets is beneficial to enhance photocatalytic activity.