Characterization and DFT investigation of CuWO₄@CMC/PVA composite with down conversion ability

This study focuses on the synthesis of CuWO₄ nanoparticles using a simple hydrothermal method and their incorporation into carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA) polymer blend through the solution casting method, resulting in CuWO₄@CMC/PVA polymer nanocomposites with varying CuWO₄ concentrations (0.0, 0.5, 1.0, 2.0, and 4.0 wt/wt%). Rietveld refinement of XRD data was performed to assess the phase purity of CuWO₄ nanoparticles and found to possess triclinic unit cells. Furthermore, the microcrystalline properties of the prepared nanocomposites were also evaluated. The surface topography of the CuWO₄@CMC/PVA nanocomposite was examined using AFM to assess its morphological features and surface roughness, while FE-SEM and SEM were employed for microstructural analysis to evaluate the morphology of nanoparticles and their distribution in the polymer matrix. The interaction between the CuWO₄ nanoparticles and the polymer matrix was rationalized using FTIR spectroscopy, complemented by DFT and TDDFT studies. Additionally, thermal properties such as melt properties and thermal stability were investigated through DSC and TGA respectively. While water contact angle measurements were utilized to assess wettability and surface energy. Optical properties such as absorbance, absorption coefficient, energy band gaps (direct and indirect), refractive index, optical conductivity were analysed and found that there was a monotonic decrease in the band gap as the nanoparticles concentration increases. Photoluminescence spectroscopy was used to analyse emission properties to understand the nanocomposites' and potential for photovoltaic and UV-blocking applications.