Electrospun Bio-zein Conductive Composites Engineered with Versatile Nanomaterials for High-Performance Supercapacitors

Abstract

Corn-farm profitability has declined because of mounting problems in the agricultural sector caused by shifting consumer preferences and environmental changes. Therefore, scientists have investigated high-value uses for agricultural waste, and Zein, a corn-derived protein, is a viable option for long-term energy storage. Although Zein has benefits, including mechanical durability and biodegradability, its low electrical conductivity necessitates its modification for use in supercapacitor (SC) electrodes. To improve electrochemical performance, this study describes the fabrication of Zein-based composite electrodes incorporating metal oxides (MOs), graphene oxide (GO), polypyrrole (PPy), and indium phosphide quantum dots (InP QDs). To increase conductivity, pyrrole was polymerised in the vapour phase after electrospinning Zein into a fibrous structure as a PPy based nano porous matrix. Moreover, the nanomaterials such as MOs, GO, QD were added to the matrix to improve its ion transport and charge storage capabilities. The successful integration of essential components was validated via material characterisation using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. A densely packed fibrous structure promoting effective ion diffusion was observed using scanning electron microscopy. Meanwhile, the electrochemical performance of the Zein-PPy-QD-GO-MO-composite-based SC demonstrated a low charge transfer resistance (Rct) and a fairly good specific capacitance (135 mF/cm²) among the electrodes of the bio-resources derived composite. The device exhibited nearly 100% coulombic efficiency and excellent capacitance retention, maintaining >70% of its initial capacitance after 6000 cycles. Thus, Zein-based bio-composites are sustainable substitutes for matrix for the traditional SC materials. By integrating conductive nanostructures and biodegradable polymers, this study promotes high-performance and ecologically acceptable energy storage solutions made from agricultural waste.