Exploring dual optical responses of Polyaniline-Fe2O3 nanocomposites for advanced optoelectronic and supercapacitor applications

Abstract

This work investigates the synthesis of nanocomposites and explores their possibility for diverse applications in electromagnetic interference shielding, sensor development, energy storage devices, and dye adsorption. We implemented an optimized electrochemical polymerization method to incorporate controlled concentrations (1, 3, 6, and 12 wt%) of Fe₂O₃ NPs into the polyaniline (PANI) matrix to investigate the influence of iron oxide nanoparticles (Fe₂O₃ NPs) on PANI composite properties. To understand structure-property relationships, a comprehensive characterization of synthesized hybrid nanocomposites was undertaken. This analysis focused on their structural properties, dielectric behavior, and linear and nonlinear optical responses. The Williamson-Hall method (W-H) was employed to determine crystallite size and account for the contribution of lattice strain within the material. Williamson-Hall analysis revealed an average crystallite size ranging from 91 to 128 nm. Interestingly, the initial incorporation of low concentrations of Fe₂O₃ NPs into the PANI matrix led to a decrease in crystallite size. This suggests an interaction between the PANI chains and the nanoparticles that hinders their crystal organization. However, this trend reversed with the addition of higher Fe₂O₃ NP concentrations, resulting in an increase in crystallite size likely due to nanoparticle aggregation. Incorporating Fe₂O₃ NPs led to more intense absorption bands and increased absorption coefficients in the nanocomposites compared to the pristine PANI film. This observation suggests enhanced light absorption efficiency within nanocomposite materials. Conversely, the dielectric constant (ε_r and ε_i), which represent a material's ability to store electrical energy, exhibited lower values in the PANI-Fe₂O₃ composites than pure PANI. PANI exhibited a high specific capacitance (C_sp) of 477 F g⁻¹, indicating its potential for efficient supercapacitor applications. This study demonstrates that Fe₂O₃ NPs effectively manipulate the nonlinear optical properties of polyaniline. The observed trends, including the decrease in crystallite size and its influence on optical parameters, underscore the unique properties of the PANI-Fe₂O₃ nanocomposite system. These findings position these materials as strong contenders for uses in optoelectronics and energy storage devices.