Effect of gamma irradiation on optical and electronic properties of PVC/CoSe/TiO ₂ nanocomposites

This study investigates the effects of gamma irradiation on the structural, optical, and electronic properties of PVC/CoSe/TiO 2 nanocomposite films, with irradiation doses ranging from 0 to 100 kGy. X-ray diffraction (XRD) analysis reveals the predominantly amorphous nature of the PVC matrix, showing a broad halo centered around 2θ ≈ 15–25°. While no new crystalline phases were observed and major peak positions remained unchanged upon irradiation, subtle variations in the broad amorphous halo’s intensity suggest potential localized rearrangements within the PVC matrix, particularly a slight decrease in overall intensity with increasing dose. Energy-dispersive X-ray spectroscopy (EDX) verifies the presence of all constituent elements (C, Cl from PVC; Co, Se from CoSe; Ti, O from TiO 2 ), confirming the successful incorporation and distribution of CoSe and TiO 2 nanoparticles within the PVC matrix. Ultraviolet-visible (UV-Vis) spectroscopy demonstrates a clear influence of gamma irradiation on the nanocomposite’s optical properties, evidenced by a redshift in the absorption edge of up to X nm (from 450 nm to 480 nm) and an increase in visible light absorption by up to Y% (15–20%) with increasing dose. These changes are attributed to a combination of radiation-induced defect formation and potential subtle structural modifications. Analysis of the volume and surface energy loss functions (VELF and SELF) further supports alterations in the electronic structure and surface properties due to irradiation. The observed tunability of optical properties and enhanced light absorption hold promise for applications in photocatalysis, solar energy conversion, and optoelectronic devices. However, the study emphasizes that these optical changes may not solely arise from gross structural changes or simple defect formation. The potential contribution of subtle changes in local atomic order, free volume, or interfacial effects, undetectable by XRD, is highlighted. Therefore, future work employing complementary techniques such as electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) is proposed to gain a more comprehensive understanding of the complex structure-property relationships in these irradiated nanocomposites and to precisely correlate the observed optical changes with specific defect types and their evolution under gamma irradiation.