# Iron oxide decorated nitrogen doped carbon derived from iron MOFs and polyaniline as binder free electrode for symmetric supercapacitors

## TL;DR

This paper presents a new binder-free electrode material made from iron oxide and nitrogen-doped carbon for efficient and stable supercapacitors.

## Contribution

A novel Fe3O4/nitrogen-doped carbon composite is developed using iron MOFs and polyaniline for high-performance symmetric supercapacitors.

## Key findings

- The 20FNC@P-PANI composite achieved a specific capacitance of 633.9 F/g at 1 A/g.
- The device retained 95.86% capacitance after 10,000 cycles at 10 A/g.
- It delivered energy and power densities of 47.52 Wh/kg and 789.99 W/kg, respectively.

## Abstract

Electrochemical supercapacitors are crucial energy storage technologies for the evolution of electric cars and the regulation/utilization of intermittent renewable resources. In his work, Fe3O4/nitrogen-doped carbon (FNC) was fabricated via an efficient, facile solvothermal synthesis of the iron-based metal-organic framework (MIL-101(Fe) and NH2-MIL-101(Fe)), followed by pyrolysis under a N2 atmosphere. The prepared FNC was mixed at different ratios with pyrolyzed polyaniline (P-PANI) to enhance the conductivity, hydrophilicity, and electrochemical performance of the fabricated electrode materials. The morphology and crystallinity of the synthesized FNC@P-PANI composites were evaluated by SEM and XRD, revealing a nanoscale architecture with good crystallinity. The electrochemical behavior of FNC, P-PANI, and FNC@P-PANI materials was studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 1.0 M Li2SO4 as a neutral electrolyte. Compared to plain FNC and P-PANI, the 20FNC@P-PANI composite showed an enhanced specific capacitance of 633.9 F/g at 1 A/g. Furthermore, the assembled device exhibited outstanding stability of 100.1% after 1,000 cycles and 95.86% after 10,000 cycles at 10 A/g. The 20FNC@P-PANI composite’s high surface area, stability, and rapid ion and electron transport facilitated its high electrochemical efficacy. Moreover, the symmetric supercapacitor device delivered superior energy and power densities of 47.52 Wh/kg and 789.99 W/kg, respectively, at 1 A/g. These favorable results suggest that it is possible to produce innovative, ecologically friendly, and commercial electrode materials based on Fe3O4 and carbon-doped nitrogen.

The online version contains supplementary material available at 10.1038/s41598-026-39173-4.