Electrocatalytic Performance Of Fe-N/C Nanocomposite Materials And Its Application In MFC

Doped carbon material has been recognized as a promising non-Pt cathode catalyst for oxygen reduction reaction (ORR). Among them, Fe-N codoped nanocarbon material as the microbial fuel cells (MFC) non-noble metal cathode catalyst for oxygen reduction has been one of the research hot spots.Herein, a new Fe-N codoped carbon material (Fe-N/C) was prepared by the carbonization of Polyaniline-Prussian blue composite (PANI-PB). The influence of preparation conditions such as carbonization temperature and potassium ferricyanide solution concentration on the electrocatalytic performance towards oxygen reduction was investigated in detail. Then, the morphology, structure and chemical composition of the synthesized Fe-N/C were characterized by various techniques including SEM, TEM, N2 adsorption/desorpotion isotherms, FTIR, Raman spectra, XRD and XPS. Results showed that the optimal potassium ferricyanide solution concentration and the carbonization temperature are 0.02 mol/L and 800～900℃, respectively.Cyclic voltammetry (CV) and rotating disk electrode (RDE) technologies were applied to investigate the catalytic properties of Fe-N/C/GC electrode towards ORR in potassium hydroxide solution, phosphate buffer solution and perchloric acid solution, respectively. It was found that the Fe-N/C modified electrodes show better oxygen reduction catalytic activity than the c-PANI and c-PB modified electrodes, suggesting the existence of synergetic effect between c-PANI (C-N) and c-PB (Fe-N) in the Fe-N/C composite:In both potassium hydroxide alkaline solution and phosphate buffer solution, the Fe-N/C composite catalyzed oxygen reduction involved four-electron transfer process, while a two-electro reduction pathway was observed in perchloric acid solution.The prepared Fe-N/C/Carbon-felt material was used as cathode in the double room MFC with dissolved oxygen as electron acceptor to investigate the MFC performance. For comparative analysis, another MFC was also established with the pure carbon felt as cathode material and the potassium ferricyanide solution as electron acceptor. Results showed that although the power output of MFC with Fe-N/C/Carbon-felt as cathode and dissolved oxygen as electron acceptor is lower than that with potassium ferricyanide as cathode electron acceptor, the Fe-N/C catalysts obviously reduced the activation loss of the modified electrode, significantly improved the cathodic oxygen reduction reaction efficiency and decreased the internal resistance of MFC. Compared to the pure carbon felt, MFC with Fe-N/C/Carbon-felt as cathode showed a faster degradation rate of COD. Besides, the output power density and internal resistance are about 1.5 W/m3 and 200 Ω, respectively, which are superior to those obtained in MFC with pure carbon felt as cathode (0.97 W/m3 and 260 Ω).