Novel mesoporous MnCo₂O₄ nanorods as oxygen reduction catalyst at neutral pH in microbial fuel cells

The aim of this work was to evaluate the comparative performance of hybrid metal oxide nanorods i.e. MnCo₂O₄ nanorods (MCON) and single metal oxide nanorods i.e. Co₃O₄ nanorods (CON) as oxygen reduction catalyst in microbial fuel cells (MFC). Compared to the single metal oxide, the hybrid MCON exhibited a higher BET surface area and provided additional positively charged ions, i.e., Co²⁺/Co³⁺ and Mn³⁺/Mn⁴⁺ on its surfaces, which increased the electro-conductivity of the cathode and improved the oxygen reduction kinetics significantly, achieved an i_o of 6.01 A/m² that was 12.4% higher than CON. Moreover, the porous architecture of MCON facilitated the diffusion of electrolyte, reactants and electrons during the oxygen reduction, suggested by lower diffusion (R_d), activation (R_act) and ohmic resistance (R_ohm) values. This enhanced oxygen reduction by MCON boosted the power generation in MFC, achieving a maximum power density of 587 mW/m² that was ∼29% higher than CON.