CuO-SnO₂/N-doped reduced graphene oxide as superior oxygen reduction electrocatalyst for microbial fuel cell

Transition metal oxides supported on carbon have emerged as robust catalysts for energy recovery and environment applications, like fuel cells. In this investigation, a series of catalysts with copper tin oxide (CuO-SnO₂) anchored over nitrogen doped reduced graphene oxide (N-rGO) namely N-rGO-CuSn, rGO-CuSn, and N-CuSn were synthesised for oxygen reduction reaction (ORR) application. Physicochemical characterization revealed a 3D porous structure in the N-rGO-CuSn catalyst, with CuSn oxides deposited on N-rGO sheets. Electrochemical characterization demonstrated that N-rGO-CuSn exhibited excellent ORR activity, with lower charge transfer resistance (5.1 Ω), comparable oxygen diffusion coefficient (5.3 × 10⁻⁵ cm²/s), higher specific capacitance (29.9 F/g), and higher poison resilience than 10% Pt/C catalysed electrodes. The synthesised catalyst was further examined as an electrocatalyst in a microbial fuel cell (MFC), which confirmed the superior ORR activity by achieving a maximum power density of 9.2 ± 0.2 W/m³. The results emphasise the promising competence of N-rGO-CuSn as a highly efficient catalyst suitable for energy and environmental applications, notably in MFCs and other fuel cell technologies.