Fabrication of CuO/ZnO composite films with cathodic co-electrodeposition and their photocatalytic performance

CuO/ZnO composite films with different atomic Cu/Zn ratios were for the first time fabricated on indium tin oxide (ITO)-coated glass substrates via a cathodic co-electrodeposition route from baths containing Zn(NO3)2 and Cu(CH3COO)2. The obtained composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Hexavalent chromium (Cr(VI)) was used as a model pollutant to evaluate their photocatalytic activity. For a bath containing Zn(NO3)2 with a certain concentration, the concentration of Cu2+ ions added into this bath play an important role in fabrication of CuO/ZnO composite films. When the Cu2+ concentration in a bath is lower, the obtained composite is a Cu-doped ZnO film. The electrodeposited CuO/ZnO composite films show higher photocatalytic activity towards reduction of Cr(VI) compared to pure ZnO both under UV and under UV–vis light illumination. Furthermore, the photocatalytic activity of CuO/ZnO composite films is related to their atomic Cu/Zn ratios. The mechanism of CuO/ZnO composite films for improvement in photocatalytic activity was also discussed.

Graphical abstractThis report presents cathodic co-electrodeposition of CuO/ZnO films and application for photoreduction of Cr(VI). Their improved photocatalytic activity can be partly attributed to a efficient interfacial separation of charges.Figure optionsDownload full-size imageDownload high-quality image (68 K)Download as PowerPoint slideResearch highlights▶ CuO/ZnO composite films are fabricated with cathodic co-electrodeposition. ▶ Cu-doped ZnO film is obtained from a bath with low Cu2+ concentration. ▶ CuO/ZnO composite films have high photocatalytic activity. ▶ Photocatalytic activity is related to atomic Cu/Zn ratios in the films. ▶ Enhancement of activity is attributed to the efficient separation of charges.