Effects of the Preparation Process on the Photocatalytic Performance of Delafossite CuCrO₂

Hydrothermal and solid-state reaction methods are commonly used to prepare the delafossite CuCrO₂ photocatalyst. It has been reported that the photocatalytic performances of CuCrO₂ samples prepared by these methods are quite different. In order to explore the possible influence of different preparation processes on the photocatalytic performance and the corresponding improvement strategies, this work compares the microstructure and physicochemical properties of the samples prepared by these two methods on the basis of optimizing the process conditions. A CuCrO₂ sample prepared by a hydrothermal method is characterized by high purity, low crystallinity, small grain size, and relatively higher photocatalytic activity. A CuCrO₂ sample prepared by a solid-state reaction method is characterized by low purity, high crystallinity, large grain size, and relatively lower photocatalytic activity. In combination with DFT calculations, it is confirmed that the CuCrO₂ sample prepared by a solid-state reaction method contains a certain amount of interstitial oxygens. Due to the presence of interstitial oxygens, CuCrO₂ has strong light absorption in the visible region, presents semimetallic ferromagnetism, and changes the carrier transport, reaction process, and rate on the electrode surface. These findings will contribute to the further development of efficient CuCrO₂-based photocatalysts.