Sunlight-activated dye degradation of ZnO/CdO-decorated graphene oxide and its antibacterial activity

Abstract

The pollution of water sources by hazardous substances such as sulfates, cyanides, and heavy metals represents a major environmental challenge. Addressing these issues requires the degradation of pollutants in wastewater to mitigate our environmental crises. Graphene oxide (GO) significantly enhances the mechanical and functional properties of GO-ZnO and GO-CdO nanocomposites, making them promising materials for applications in both sensors and catalysts. In this context, two optically active metal oxide-decorated graphene oxides (GO-ZnO and GO-CdO) were synthesized, and their photocatalytic efficacy against methylene blue (MB) was evaluated. Using an FT-IR spectrophotometer, the vibrational modes of hydroxyl (OH), carbonyl (C=O), and carboxylic (COOH) groups were identified. Raman spectroscopy analysis provided additional insights, confirming these vibrational properties. These materials exhibited peak photon absorption (λmax) at 242 nm and an optical band gap of 3.7 eV. Frontier molecular orbital (FMO) analyses indicated significant electronic charge transfer on the materials' surfaces, demonstrating their excellent capacity for adsorbing MB. An optimal catalyst dosage of 50 mg was found to be most effective in accelerating the degradation of MB. Additionally, variations in the initial pH of the solution showed a direct correlation, with higher pH levels leading to enhanced degradation efficiency, reaching up to 97% after 120 minutes. Quantum Theory of Atoms in Molecules (QTAIM) analyses revealed that MB is extensively adsorbed and degraded through a series of hydrogen bonding interactions. Moreover, experimental results indicate that both materials have a significant impact on bacterial destruction, suggesting their potential as novel antibacterial agents.