We report enhanced catalytic action of a series of copper(II)-oxide-single-walled carbon nanotube (CuO-SWCNT) composite photocatalysts (abbreviated as CuO-SWCNT-0.5, CuO-SWCNT-2, and CuO-SWCNT-5, where 0.5, 2, and 5 represent the calcination time in hours) synthesized via recrystallization followed by calcination. The photocatalytic performance of the fabricated nanocomposites was examined by evaluating the degradation of methylene blue (MB) under irradiation with visible light. All of the as-fabricated nanocomposites were effective photocatalysts for the photodegradation of a MB solution; however, the CuO-SWCNT-5 displayed the best photocatalytic ability among the investigated catalysts, achieving 97.33% degradation of MB in 2 h under visible-light irradiation. The photocatalytic action of the nanocomposites was remarkably higher than that of pristine CuO nanocrystals fabricated using the same route. The recyclability of the photocatalyst was also investigated; the CuO-SWCNT-5 catalyst could be reused for three cycles without substantial degradation of its catalytic performance or morphology.

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ZnO nanoparticles (ZnO-NPs) were synthesized by a straightforward modified thermal method using only one chemical: zinc acetate dihydrate. The process is environmentally safer than other methods because it does not involve other chemicals or a catalyst, acid, or base source. X-ray diffraction analysis indicated that the ZnO-NPs crystallize in the hexagonal wurtzite structure. The UV–vis absorption spectra revealed a marked redshift, which is critical for enhanced photocatalytic activity. We used methylene blue for photocatalytic activity tests and found an excellent degradation percentage (99.7%) within a short time (80 min). The antibacterial activity of the synthesized ZnO-NPs was tested against Escherichia coli at different concentrations of ZnO-NPs. The analysis revealed that the minimum inhibitory concentration (MIC) of the ZnO-NPs against E. coli was 30–50 μg/mL. Our ZnO-NPs were found to be more effective than previously reported ZnO-NPs synthesized via other methods.

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