Electrochemical oxide sulfide in an air-cathode fuel cell with manganese oxide/graphite felt composite as anode

Abstract

Abstract Sulfide found in wastewaters and industrial off-gases is a toxic and highly corrosive pollutant. The air-cathode fuel cell has great potential for simultaneous elemental sulfur (S0) and electricity recoveries from sulfide. Here, manganese oxide (MnOx) is in-situ synthesized on graphite felt (GF) surface in a solvothermal system at different ethanol/water (E/W) volume ratios, and the prepared MnOx/GF composites are used as the anodes of air-cathode fuel cell for spontaneous sulfide electrochemical oxidation. The performance of these MnOx/GF composite anodes is comprehensively evaluated in term of sulfide removal, sulfur recovery and electricity production efficiencies. The results show that the manganese oxide loading on the GF presents as MnO2 at E/W ratio of 0/10. When the E/W ratio is greater than 3/7, the obtained manganese oxides are all Mn3O4 and its particle size and loading on the GF decrease with the increase of ethanol concentration. The Mn3O4/GF composite prepared at E/W ratio of 3/7 has a great potential in catalyzing the electrochemical oxidation of sulfide in the air-cathode fuel cell. Compared with GF, the Mn3O4/GF composite anode shortens the time for complete sulfide oxidation from 120 h to 60 h. Meanwhile, the sulfur recovery efficiency and coulombic efficiency are as high as 78.4% and 71.5%, respectively.