Synthesis of Binary Metal Doped CuO Nanoarchitecture for Congo red dye Removal: Synergistic Effects of Adsorption and Mineralization Techniques

Abstract

Herein, a microwave-assisted fabrication technique has been practiced for the generation of pristine CuO and Cd/Zn co-doped CuO (Cu0.94Cd0.03Zn0.03O) nanopowders with the identical weight ratio of cadmium and zinc metals. The structure, chemical nature, shape, and optical response of CuO and Cu0.94Cd0.03Zn0.03O were assessed by PXRD, FESEM, FTIR, and UV–vis analytical techniques. PXRD results affirmed that CuO and Cu0.94Cd0.03Zn0.03O have developed in a single monoclinic phase; other extra phases are absent. The crystallite sizes of CuO and Cu0.94Cd0.03Zn0.03O were identified as 18.5 nm and 14.39 nm. The FESEM image of the Cu0.94Cd0.03Zn0.03O sample demonstrated a nanosheet-like morphology that was developed after the co-doping of Zn and Cd metal ions. FTIR graphs established the occurrence of Cu–O main bonds in both fabricated nanopowders. The UV–vis examination demonstrated that Cd and Zn co-doping has substantially reduced the energy gap of pristine CuO from 2.0 eV to 1.54 eV. This massive reduction in CuO bandgap assists it in catching extra photons to stimulate valence-band electrons and hence boosts the activity of the catalyst under sunlight irradiations. Moreover, including Cd and Zn has also effectively hindered the e−/h+ recombination in CuO throughout the photocatalysis process. The photocatalytic activities of pristine CuO and Cu0.94Cd0.03Zn0.03O nanosheets were probed against Congo-red (CR) pollutants under sunlight irradiations. The mineralization efficiency was detected as maximum (∼87.88%) for Cu0.94Cd0.03Zn0.03O nanosheets in contrast to pristine CuO nanostructures. Cu0.94Cd0.03Zn0.03O nanosheets, due to their astonishing properties, could be an economical alternative in creating intelligent strategies for mineralizing organic pollutants in industrial effluents.