CuO Nanoparticles for Effective Photocatalytic Methylene Blue Dye Degradation: Kinetic, Thermodynamic, and Mechanistic Role of Reactive Species

ABSTRACT In this study, copper oxide nanoparticles (CuO NPs) were synthesized by a low‐cost precipitation method. A Highly crystalline monoclinic structure was confirmed by x‐ray diffraction (XRD). The seed‐like morphology of the nanoparticles was obtained from field emission scanning electron microscopy (FESEM), confirming the stability of the prepared nanoparticles supported by TGA and zeta potential studies. The degradation of Methylene Blue (MB) dye has been investigated by the photocatalytic activity in the presence of H 2 O 2 . From the photocatalytic activity study of the nanoparticles, the degradation efficiency was found to be 95% in 15 min under visible light exposure. The reaction kinetics were studied using the pseudo‐first‐order reaction, and thermodynamic parameters were calculated. The activation enthalpy and entropy were found to be 46.30 kJ.mol −1 & −0.11 kJ.K −1 .mol −1 , which supports the entropically favorable condition for dye degradation on the addition of the catalyst. To know the reusability of the prepared nanoparticles, the recyclability studies were conducted, which confirm the stability through a period of five cycles. This integrated strategy of facile synthesis, fast degradation, and detailed mechanistic validation highlights the significant potential of the prepared CuO nanoparticles for real‐world environmental remediation applications.