Zinc oxide (ZnO) is a promising photocatalyst for organic pollutant degradation, but its wide band gap and rapid electron–hole recombination limit its visible-light and sunlight-driven activity. This research aims to address these shortcoming by synthesizing ZnO nanoparticles decorated with MWCNTs using solution casting and ultrasonication. A comprehensive investigation of pristine ZnO and ZnO/MWCNT composites evaluated their structural, optical, and photocatalytic properties. Photocatalytic performance was assessed by degrading methylene blue (MB) dye under sunlight irradiation under various conditions, including catalyst dosage, dye concentration, pH, temperature, and irradiation time. XRD analysis confirmed crystallite sizes of 14-18 nm for both pristine and MWCNT-decorated ZnO. The band gap also decreased from 3.19 eV to 3.05 eV, thereby enhancing visible-light absorption. The MWCNT-decorated ZnO composite exhibited superior photocatalytic activity, achieving a degradation efficiency of 99.20% after 120 minutes of sunlight irradiation, compared with 86.69% for pristine ZnO. The degradation kinetics followed a pseudo-first-order model, with an apparent rate constant of 0.03853 min -1 for the MWCNT/ZnO composite, significantly higher than that of pristine ZnO (0.01428 min -1 ). These results demonstrate that MWCNT incorporation effectively enhances the photocatalytic performance of ZnO by improving charge separation and reducing electron-hole recombination, supporting its potential as an effective, sunlight-driven photocatalyst for treating dye-polluted wastewater.
Manjhu et al. (Fri,) studied this question.
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