A comparative study on plate-like and flower-like ZnO nanocrystals surface photovoltage property and photocatalytic activity

ZnO nanostructures materials with two-dimensional (2D) plate-like and three-dimensional (3D) flower-like morphologies have been synthesized via facile hydrothermal process. Scanning electron microscopy (SEM), high resolution transmission electron microscope (HRTEM) and X-ray diffraction (XRD) have been used to characterize the samples. We have compared the surface photoelectric properties of flower-like ZnO with that of plate-like ZnO by means of surface photovoltage (SPV), field-induced surface photovoltage (FISPV), transient photovoltage (TPV) and surface photocurrent (SPC) techniques. Based on the photovoltage responses, the influence of the morphology on transfer characteristics of photogenerated charge carriers was discussed. The synthesized flower-like ZnO exhibited more efficient separation and transfer properties of photogenerated charge carriers than that of plate-like ZnO in the UV region due to the special flower-like hierarchical nanostructures. We have also evaluated the photocatalytic activity of the ZnO samples by photodegradation efficiency of RhB. The experiments demonstrated that RhB in aqueous solution was more efficiently photodegraded using flower-like ZnO than plate-like ZnO. The results also show the consistency between the carrier dynamics of photogenerated electron–hole pairs and photocatalytic activity.

► Flower-like ZnO possesses higher specific surface area compared to plate-like ZnO.
► Flower-like ZnO exhibits an efficient separation of photogenerated charge carriers.
► Flower-like ZnO shows better activities in the UV region than the plate-like ZnO.
► The SPV response of plate-like ZnO appeared in the visible region by field-induced.
► The correlation among the morphology, surface photovoltage property and photocatalytic activity is studied in this work.