Egg albumin‐templated Fe 3 O 4 @polyindole nanocomposites as high‐performance electrodes for flexible supercapacitors

The rapid rise in global energy demand and the transition toward renewable energy sources have intensified the search for sustainable and high‐performance energy storage systems. Supercapacitors, with their exceptional power density, fast charge–discharge kinetics, and long‐term cycling stability, have emerged as promising candidates to complement or replace conventional batteries in advanced applications such as smart power grids, electric vehicles, and flexible electronics. In this work, we report a sustainable and environmentally benign strategy for fabricating Fe 3 O 4 @polyindole (Fe 3 O 4 @PIn) nanocomposites using egg albumin as a natural bio‐template. The bio‐templated Fe 3 O 4 nanoparticles were subsequently integrated with conductive polyindole and deposited onto flexible carbon cloth, producing a hybrid electrode with enhanced electrochemical activity and structural stability. Structural and morphological analyses were performed which confirmed the homogeneous dispersion of Fe 3 O 4 within the polyindole matrix, while the carbon cloth provided a three‐dimensional conductive backbone. Electrochemical studies revealed that the carbon cloth–Fe 3 O 4 @PIn electrode delivered a high specific capacitance of 585 F g −1 at 1 A g −1 in 1 mol L −1 H 2 SO 4 electrolyte, along with good cycling stability, retaining 73% capacitance after 5000 cycles.