PVC polymer/ZnO/NiO/Co3O4 nanocomposites: Toward improved optical properties

Abstract

Undoped and doped polyvinyl chloride (PVC) with zinc, nickel and cobalt oxides, ZnO/[(1−x)NiO/xCo₃O₄], composites were fabricated using co-precipitation and casting techniques. The different phases present in the nanofiller ZnO/[(1−x)NiO-xCo₃O₄] mixed oxides were determined using synchrotron x-ray diffraction technique. X-ray diffraction, scanning electron microscopy (SEM) images and energy dispersive spectroscopy (EDS) analysis techniques were used to investigate the structure, composition, and morphology of pure and loaded PVC with nanofiller oxides. In general, compared with pure PVC, the absorbance was greatly enhanced, especially in the UV region, upon loading ZnO/[(1−x)NiO-xCo₃O₄], but it changed irregularly with the cobalt oxide (Co₃O₄) content (x). The direct and indirect optical band gaps of pristine PVC (4.14, 4.12 eV) reduced irregularly to minimum values 3.97 and 3.23 eV respectively for the polymer doped with ZnO/[0.3NiO/0.7Co₃O₄]. The refractive index was enhanced in the visible and IR regions and attained its highest value for PVC doped with zinc oxide/nickel oxide (ZnO/NiO) only (x = 0.0). NiO and Co₃O₄ ratios affect the linear and nonlinear optical parameters. The emitted spectra from pure and doped PVC polymers with the composite oxides [ZnO/[(1−x)NiO-xCo₃O₄] under different excitation wavelengths were also explored. The FL intensity enhanced for the excitation wavelengths (λ_exc) = 380 and 434 nm but quenched for λ_exc = 317 nm. The loaded polymers absorb UVA, UVB, and UVC rays and are good candidates for solar cell applications.