Preparation and characterization of a novel cobalt-substitution cadmium aluminate spinel for the photodegradation of azo dye pollutants

Abstract

Modern-year organic contaminants have been highly observed in ecosystems since they are not removed entirely and remain dangerous. Semiconductor binary oxide photocatalysts have been well accredited as capable technology for ecological contaminants degradation in the existence of visible irradiation. In this research, novel Co ions doped CdAl2O4 materials were fabricated by a facile co-precipitation approach. The fabricated pure and Co-doped CdAl2O4 exhibited the typical peaks of CdAl2O4 with the Eg of 3.66, 3.24, 2.57, and 2.41 eV respectively. The HR-TEM microstructures revealed that the Co (0.075 M) doped CdAl2O4 has rod-like morphology, and some places are spherical with particle sizes reaching 21 nm. The PL peaks of the Co (0.075 M)-CdAl2O4 are much lesser than that of the other dopant and pure CdAl2O4, representing much more effectual separation of generated e− and h+ at the interface which in fact outcomes in superior expected photodegradation behaviours. The Co (0.075 M)-CdAl2O4 catalyst demonstrated the highest performances of 92 and 94% toward the degradation of both dyes, respectively, owing to the lowest e− and h+ recombination rate. The Co (0.075 M) doped CdAl2O4 photocatalyst revealed outstanding reusability and stability under visible irradiation, retaining the performance of about 83 and 86% after the fifth consecutive run of BB and BG elimination. A probable photodegradation mechanism of Co (0.075 M) doped CdAl2O4 was suggested since the photoexcited h+, OH− and O2− species contributed to the removal process, and that was affirmed by the scavenging test and ESR analysis. This research offers new ways to improve the photodegradation performance of the Co-doped CdAl2O4 catalyst that will be employed in pharmaceutical applications and wastewater treatment.