Investigating the photocatalytic properties of copper cobaltite and copper cobaltite-reduced graphene oxide composites for organic dye removal under sunlight irradiation

Abstract

ABSTRACT Scientists are researching new catalysts that can be used in the photocatalytic degradation of water pollution caused by organic dyes. The challenges of photocatalysis are the high recombination rate and low conductivity of photogenerated electrons (e−) and photogenerated holes (h+). To address these issues, the synthesis of hetero-structured composites can provide a solution. Reduced graphene oxide (rGO) can enhance the photocatalytic properties of hetero-structured composite when used together in a composite material. The combination of these materials can lead to improved performance in the degradation of organic dyes, such as methyl blue (MB), in wastewater treatment. In this study, the preparation of copper cobaltite (CuCo2O4) and copper cobaltite-reduced graphene oxide (CuCo2O4-rGO) composites was carried out using an economical chemical method, resulting in a high-performing photocatalyst. The structural, morphological and functional properties of the composites were characterised using X-ray Diffractometry (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), and Fourier Transform Infrared Spectroscopy (FTIR). Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-vis DRS) revealed the optical band gap 1.52 eV and 1.44 eV for CuCo2O4 and CuCo2O4-rGO composites respectively. Photoluminescence Spectroscopy (PL) of CuCo2O4-rGO showed peak with decreased intensity as compared to CuCo2O4, which is indicative of low recombination rate. Brunauer-Emmett-Teller (BET) analysis showed that CuCo2O4-rGO has high surface area 125.479 m2/g and large pore volume 0.03850 cc/g. Narrow arc radius of Nyquist plot of CuCo2O4-rGO obtained by Electrochemical Impedance Spectroscopy (EIS) demonstrated better charge separation than CuCo2O4. The findings of this study demonstrated that both synthesised photocatalysts exhibit exceptional photocatalytic activity for the degradation of dye under solar irradiation but rGO incorporated CuCo2O4 showed more improved photocatalytic behaviour as compared to CuCo2O4. This improvement is credited to large surface area and high electrical conductivity of rGO, which facilitated the transfer of photogenerated electrons from CuCo2O4 to rGO, reduced the chance of recombination and increased the overall efficiency.