Splitting growth of novel CuO straw sheaves and their improved photocatalytic activity due to exposed active {110} facets and crystallinity

Abstract

In this paper, the novel straw sheaf-like CuO single crystals have been, for the first time, prepared through a facile two-step process: hydrothermal and subsequent calcination. We have mainly investigated the influences of the copper(II) concentration, the added amount of hexamethylenetetramine (HMT), reaction temperature and time on the samples. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and nitrogen sorption isotherms. The results show that the formed CuO straw sheaves are fairly uniform, and the single straw grows preferentially along the [001] orientation. It is proposed that the CuO straw sheaves form by a crystal splitting growth process. Furthermore, under visible-light irradiation, the CuO straw sheaves exhibit 5.3 times higher activity than the irregular sample for the degradation of rhodamine B (RhB), which has been ascribed to the exposed {110} facets and high crystallinity.