Enhanced photocatalytic degradation of congo red by solvothermally synthesized CuInSe2–ZnO nanocomposites

Abstract

Efficient photocatalysts of CuInSe₂–ZnO nanocomposites were prepared via a solvothermal method using a mixed solvent of ethylenediamine and ethanol (volumetric ratio of 1 : 1). The products were characterized by SEM, EDX, XRD, PL, BET surface area, PZC and DRS UV-vis techniques and used for photo-degradation of congo red. The characterization results showed that crystallite size, BET surface area and optical absorption of the samples varied significantly with the addition of CuInSe₂ to ZnO. The nanocomposites show absorption edges in the ultraviolet and visible regions depending on their CuInSe₂ content. The optical band gap values of these nanocomposites were calculated to be about 3.37–2.1 eV, which show a red shift from that of pure ZnO. These red shifts indicate the incorporation of CuInSe₂ in the zinc oxide lattice. In the investigation of the photocatalytic activity of the samples, the effects of the experimental parameters including pH, congo red concentration, CuInSe₂ content and irradiation sources of UV and visible light have also been studied. Addition of CuInSe₂ was effective in improving the photocatalytic activity remarkably. The highest percentage removals of 99.8% and 80.3% are observed for the photocatalyst containing 10 wt% CuInSe₂ after 90 and 120 min under UV and visible irradiation, respectively. Also, a possible removal mechanism of the samples is proposed. It could be considered as a promising photocatalyst for dye degradation.