An eco-friendly technique is developed for breaking down microplastic (MP) waste such as low-density polyethylene (LDPE), polyrpopylene (PP), polyvinyl chloride (PVC), and polyethylene terephthalate (PET) using nickel oxide (NiO) nanoparticles (NPs) made via sol–gel synthesis under sunlight. Many characterization techniques, including UV–vis DRS, FT-IR, XRD, HR-TEM, SEM–EDX analysis, XPS, GC–MS, and TGA analyses, were used to examine the optical and structural properties of materials synthesized using the sol–gel method. The findings of the degradation investigation indicate that the NiO/PET nanocomposites (NCs) films exhibited higher photocatalytic activity in comparison to the NiO/LDPE, NiO/PP, and NiO/PVC films. Because of their increased excellent suppression and optical absorption of photo-produced charge carrier recombination, NiO NPs exhibited greater photocatalytic degradation of PET films. PET films containing 2% weighted NiO NPs degraded by approximately 41.64% in just 30 days (240 h) under visible light in comparison to the NiO/LDPE, NiO/PP, and NiO/PVC NCs films. FT-IR study verified the production of carbonyl groups (-C = O) at 1725–1705 cm−1 in the degradation products of LDPE, PP, PVC, and PET. The crystallinity and carbonyl indexes (CI) of the NiO/PET NCs films were as much as 30.0% lower than those of the NiO/LDPE, NiO/PP, and NiO/PVC films. The intermediate groups produced during the photodegradation of LDPE MPs were determined using GC–MS analysis. The major goal of this study is to provide an ecologically acceptable approach for photocatalytic degradation of MP waste using sol–gel synthesized NiO NPs.
