The Impact of Doping Concentration on the Structural and Optical Properties of Polyvinyl Chloride/Nickel Oxide Nanocomposite Films: Utilization in Catalytic Degradation of Methyl Red Dye

The objective of this research is to explore the photocatalytic properties of poly(vinyl chloride) (PVC) films, both pure and doped with varying concentrations of nanoscale nickel oxide (NiO), fabricated using the spin-coating technique. The concentrations of NiO used were 8%, 10%, and 20%. Various analytical methods were employed to characterize the samples. The presence of NiO nanocrystals within the PVC films was confirmed through X-ray diffraction, Raman spectroscopy, and infrared spectroscopy. X-ray diffraction analysis revealed an average particle size of 12 nm for the NiO. Raman spectroscopy of the nanocomposites showed additional low-intensity lines characteristic of the NaCl phase of NiO cubic (NaCl type) within the PVC host matrix, indicating excellent crystalline quality with low defect density. FTIR infrared spectroscopy confirmed the presence of peaks corresponding to the Ni–O bond vibration, with increased visibility of the absorption band of NiO as doping percentages increased. Optical analysis revealed distinct differences between the spectra of pure and doped matrices. Doping led to increased absorption, characterized by the emergence of absorption bands and a redshifted absorption edge compared to the bulk semiconductor. The optical band gap of the nanocomposites decreased with increasing NiO concentration, ranging from 3.71 to 3.90 eV. PVC/NiO nanocomposites exhibited broad luminescence across the visible to near-UV range, suggesting potential applications in optical systems operating within this spectral range. Photocatalytic activity assessments demonstrated that the inclusion of NiO nanoparticles enhanced the efficiency of the composites under UV light. The (PVC/20% NiO) sample exhibited a 65% efficiency in removing MR within 100 min, comparable to other samples with lower efficiency. The photodecomposition reaction of MR followed first-order kinetics, characterized by a rate constant (k) of 0.0098 min −1 .