Ti3C2 supported transition metal oxides and silver as catalysts toward efficient electricity generation in microbial fuel cells

Abstract

The oxygen reduction reaction (ORR) has been regarded as a bottleneck in air-cathode microbial fuel cells (MFC). Herein, transition metal oxides and silver were used in combination with a conductive and hydrophilic MXene (Ti₃C₂) for ORR. The transition metal oxides could facilitate oxygen adsorption and OO bond dissociation to improve the ORR catalytic performance of catalysts, and silver was capable of increasing the ORR kinetics and decreasing the activation overpotential significantly. Ti₃C₂–M_xO_y–Ag exhibited high ORR activity with a direct four-electron and indirect four-electron pathway in a neutral medium. In MFCs, the maximum power density was achieved by Ti₃C₂–MnO₂–Ag (418.09 mW m⁻²), which was 41% higher than that of Ag–Ti₃C₂ (295.78 mW m⁻²) and 10.8 times that of Ti₃C₂ (38.89 mW m⁻²). This could be attributed to the synergistic effect between transition metal oxides and silver to promote ORR.