Enhanced cathode performance of Fe2O3, boron nitride-doped rGO nanosheets for microbial fuel cell applications

Abstract

Iron(III) oxide (Fe₂O₃) and boron nitride (BN)-doped reduced graphene oxide (rGO) nanosheets were prepared successfully using a surfactant-free hydrothermal method. Through this method, one-dimensional Fe₂O₃ nanorods and boron nitride were incorporated into rGO nanosheets. The hybrid nanocomposite (rGO–BN–Fe₂O₃) was analyzed by X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction, and X-ray photoelectron spectroscopy. HR-TEM revealed the Fe₂O₃ nanorods to have a mean size of 20–30 nm with a uniform distribution distributed over the rGO nanosheets. In this study, the performance of the graphene-based hybrid nanocomposites, rGO–BN–Fe₂O₃, was assessed using novel cathode catalysts in a single-chamber-air-cathode microbial fuel cell (MFC). MFCs with different catalyst loadings (single layer (SL), double layer (DL), and triple layer (TL)) were fabricated. The electrochemical performance of the MFCs was analyzed by cyclic voltammetry and impedance analysis. The MFCs with the rGO–BN–Fe₂O₃ hybrid nanocomposite cathode showed higher maximum power densities (81%) than those with the rGO–BN and rGO–Fe₂O₃ composites. The MFCs with a cathode containing a DL loading of the rGO–BN–Fe₂O₃ hybrid nanocomposite showed a high power generation of 1673 ± 11 mW m⁻² and an OCP of 663 ± 4 mV compared to that generated with the other MFC-SL and MFC-TL loadings, respectively. The double-loaded cathode rGO–BN–Fe₂O₃ hybrid nanocomposite MFCs produced 81% of the predicted power density for Pt/C MFCs, 2066 ± 15 mW m⁻². Therefore, the considerable increases in power density highlight the potential of the rGO–BN–Fe₂O₃ hybrid nanocomposite cathode as a material for MFC applications. The double loaded catalyst of the rGO–BN–Fe₂O₃ hybrid nanocomposite cathode, is a promising, less expensive green material for constant power generation and prolonged operation of MFCs compared to the platinum on carbon (Pt/C) electrode.