Preparation of CuCrO2 and the photocatalytic properties of its composites

Delafossite CuCrO2 was prepared with Cr(NO3)3 and Cu(NO3)2 by the semi-wet method via two different routes. The samples were characterized with thermogravimetry-differential scanning calorimetry, X-ray diffraction, diffuse reflectance ultraviolet-visible spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy techniques. It was shown that addition of Cr(OH)3 precipitated with aqueous ammonia solution into aqueous Cu(NO3)2 solution is a suitable route to synthesize CuCrO2. In the calcination process, the precursor transformed into CuCrO2 in the sequence: Cr(OH)3 → CuCrO4 → CuCr2O4 → CuCrO2, as verified by the TG-DSC and XRD results. The composites of CuCrO2-WO3 and CuCrO2-ZnO prepared by the grinding method show higher activity than CuCrO2 in the photocatalytic splitting of water into hydrogen under the irradiation of a high-pressure mercury lamp or a xenon lamp.