Microbial electrosynthesis of acetic acid from carbon dioxide using a bimetallic-granular activated carbon cathode

Development of highly stable, conductive, biocompatible and cost-effective cathode is crucial for scaling up microbial electrosynthesis (MES). Bimetallic cathodes have gain importance in recent times due wide application. Current study utilized a bimetallic (nickel and iron) impregnated granular activated carbon (Ni-Fe-GAC) cathode in microbial electrosynthesis. Ni-Fe-GAC cathode was prepared via treating GACs in a mixed solution of nickel chloride and iron sulphate. Deposition of metals on GAC facilitates the improved electron transfer and biofilm formation on the GAC surface, giving 1.4 times higher acetate production than plain GAC (control). Scanning electron microscopy (SEM) confirmed the well adaptation of anaerobic microbes on the surface of Ni-Fe-GAC cathode. Linear sweep voltammetry (LSV) confirmed the better electrochemical performance of Ni-Fe-GAC cathode. A regeneration test was also conducted via acid washing to remove metals from Ni-Fe-GAC followed by reloading. Regeneration successfully restored cathode performance, making Ni-Fe-GAC suitable for long-term application.