Multifunctional properties of iron oxide nanorod-reinforced hydroxypropyl methylcellulose/chitosan biopolymer electrolytes for energy storage applications

Abstract

Abstract Biodegradable hydroxypropyl methylcellulose/chitosan (HPMC/Cs) polymer electrolytes reinforced with iron oxide (Fe 2 O 3 ) nanorods were fabricated via a solution casting method, and their structural, optical, dielectric, and ion transport properties were investigated. XRD and FTIR analyses confirmed strong interfacial interactions between Fe 2 O 3 nanorods and HPMC/Cs matrix, resulting in reduced crystallinity and enhanced amorphous content, which facilitates ion mobility. UV–Vis spectroscopy showed a gradual narrowing of both indirect and direct optical band gaps, due to the formation of localized states and an increase in structural disorder. Dielectric measurements revealed high dielectric constants (ε′) up to ~ 3400 for the sample containing 4.0 wt% Fe 2 O 3 . Nyquist plots and equivalent-circuit modeling depressed decreased bulk resistance and improved interfacial capacitance, confirming improved ionic conduction. These synergistic improvements demonstrate that Fe 2 O 3 nanorods significantly enhance polymer–filler interactions, structural disorder, and ion transport within the HPMC/Cs matrix. The resulting nanocomposite electrolytes exhibit improved dielectric and ionic properties, making them promising candidates for flexible energy storage and eco-friendly electronic applications.