The role of binary transition metal Cobalt-Nickel sulfide as an anode catalyst in specifically selection of Desulfuromonas and improved performance of microbial fuel cell

Abstract

Microbial fuel cell (MFC) has been regarded as a promising approach for electricity generation by oxidizing organic wastewater, yet the low power density still hinders its factual application. By replacing oxygen with lower electronegative sulfur, the sulfide with better stability, high biocompatibility and lower internal resistance could be obtained, which is suitable for the requirements of anode materials. However, there are few studies on sulfide as anode to improve MFC from the perspective of electrochemical performance and bacteria. Hence, a capacitive and biocompatible NiCo2S4 is prepared by hydrothermal method and utilized as anode material on a titanium network in MFC. Compared with the NiCo2O4, the charge transfer resistance of the NiCo2S4 modified electrode decreases from 17.48 Ω to 8.76 Ω. Moreover, the MFC with NiCo2S4 anode obtains a faster start-up time and maximum power density of 8.40 W/m3, nearly 1.63 times higher than that of NiCo2O4 (5.13 W/m3). The microbial community analysis further exhibits that the NiCo2S4 significantly and specifically selected exoelectrogens, Desulfuromonas (42.74 %), with improved associated metabolic pathways, indicating a more efficient power generation process. The high performance could be ascribed to the fact that NiCo2S4 decreases the inner resistance and improve the efficiency and kinetics of extracellular electron transfer (EET), while its unique biocompatibility allows exoelectrogens to adhere to the bioanode selectively. This study demonstrates the potential of binary transition metal sulfide as the anode material for MFC from the perspective of electricity production and microbial community structure.