Eco-friendly synthesis of an α-FeO/rGO nanocomposite and its application in high-performance asymmetric supercapacitors.

This work presents an innovative and environmentally friendly biological synthesis approach for producing α-FeO nanoparticles (NPs) and the successful synthesis of α-FeO/reduced graphene oxide (rGO) nanocomposites (NCs). This novel synthesis route utilizes freshly extracted albumin, serving as both a reducing agent and a stabilizing agent, rendering it eco-friendly, cost-effective, and sustainable. A combination of characterization techniques including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and field emission scanning electron microscopy (FE-SEM) was employed to predict and confirm the formation of the as-synthesized α-FeO NPs and α-FeO/rGO NCs. Transmission electron microscopy (TEM) verified the anisotropic nature of the synthesized nanoparticles. To gain insight into the enhanced capacitance of the α-FeO/rGO NCs, a series of electrochemical tests, namely cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), and stability assessments, were conducted in a conventional three-electrode configuration. Furthermore, a two-electrode asymmetric supercapacitor (ASC) device was fabricated to assess the practical viability of this material. The α-FeO/rGO NCs exhibited a remarkable potential window of 2 V in an aqueous electrolyte, coupled with exceptional cycling stability. Even after undergoing 10 000 cycles, the capacitive retention exceeded 100%, underlining the promising potential of this material for advanced energy storage applications.