Capacitive bio–electrocatalyst Mxene@CoMo–ZIF sulfide heterostructure for boosted biofilm electroactivity to enhance renewable energy conversion

Abstract

Microbial Fuel Cells (MFC), as a technology that utilizes microbial metabolic activity to convert organic matter into electrical energy, has the dual advantage of efficient use of organic matter and renewable energy potential. However, the underdeveloped extracellular electron transfer (EET) between biofilm and anode and its weaker colonization are the main factors limiting the power enhancement and energy conversion in microbial fuel cells (MFCs). Therefore, interfacial properties of catalysts loaded on electrodes are the key to rise these restrictions. In this work, a capacitive bio–electrocatalyst has been successfully prepared through ion exchange and in–situ etching methods to anchored Co₉S₈–MoS₂–CoMo₂S₄ (CMCS) on few–layered Mxene (MX). MX applied as substrate could effectively inhibit the stacking of CMCS particles and increase reactive sites, EET efficiency and redox reaction rates. Hence, the as–prepared powders were coated on carbon felt utilized as bio–electrocatalyst in MFCs. The MFC with MX@CMCS/CF achieved significant faster start–up time and maximum power density of 6.01 W m⁻³, higher than that of CMCS (5.34 W m⁻³), MX@CoMo–ZIF (5.11 W m⁻³) and CoMo–ZIF (2.74 W m⁻³). Biofilm community analysis on anode surface indicated that MX@CMC specifically selected the electrogenic bacteria, Desulfuromonas, denoting a more effective electricity production process. The high performance could be attributed to internal resistance reduction of MX@CMCS and promotion of flavin–related protein expression. This study validated the prospective potential of MX and sulfide heterostructure as capacitive bio–electrocatalyst materials for MFCs on power generation, energy regeneration and microbial community structure.