Materials Research Express (Jan 2022)
Enhanced optical and electrical properties of CeO2NPs/chitosan nanocomposites
Abstract
Cerium oxide nanoparticles (CeO _2 NPs) of different ratios ( x = 5, 10, 15, and 20 in wt %) are successfully incorporated into chitosan (CS) to synthesize CeO _2 NPs/CS nanocomposites by solution cast method. FTIR and XRD analysis confirmed the effective incorporation of CeO _2 NPs into chitosan nanocomposites. TGA and DTG showed that the thermal stability of the as-prepared nanocomposites is improved. The CeO _2 NPs/CS nanocomposites exhibited enhanced light absorption capacity in the UV-visible range as x increases, owing to the CeO _2 NPs’ large bandgap. The transmittance of UV decreased for x = 10 and 15 nanocomposites. Light scattering enhanced for x = 5 and 10 nanocomposites, increasing reflectance. Compared to CS (5.3 eV), the optical energy bandgap lowers to 4.94 eV and 5.1 eV, respectively. Impedance spectroscopy research validates the impedance spectroscopy parameters’ dependency on CeO _2 NPs concentrations. Because of the growth of multiple polarization types, generating interfaces of numerous defects, and space charge polarization, the dielectric constant increases with increasing x (up to x = 15). The dc conductivity ( σ _DC ) and the frequency exponent ( S ) are estimated using the universal Josher’s power law and applied to the ac conductivity data ( σ _AC ). Obviously, ( S ) decreases with increasing temperature, which refers to the electrical conductivity that follows the hopping mechanism. In addition, according to the CBH model, the Coulomb barrier of charge carriers ( U m) is estimated, showing decreasing values as increasing x and recording the lowest value for x = 15 nanocomposites. Nyquist plots (Z″&Z′) indicate one semicircle arc behavior for all samples. As x rises, the radius of semicircular arcs reduces, suggesting that ( σ _DC ) increases. The enhanced characteristics of CeO _2 NPs/CS nanocomposites make them suitable for future bio-applications.
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