A Fe-N-C catalyst with highly dispersed iron in carbon for oxygen reduction reaction and its application in direct methanol fuel cells

Exploring non-precious metal catalysts for the oxygen reduction reaction (ORR) is essential for fuel cells and metal–air batteries. Herein, we report a Fe-N-C catalyst possessing a high specific surface area (1501 m2/g) and uniformly dispersed iron within a carbon matrix prepared via a two-step pyrolysis process. The Fe-N-C catalyst exhibits excellent ORR activity in 0.1 mol/L NaOH electrolyte (onset potential, Eo = 1.08 V and half wave potential, E1/2 = 0.88 V vs. reversible hydrogen electrode) and 0.1 mol/L HClO4 electrolyte (Eo = 0.85 V and E1/2 = 0.75 V vs. reversible hydrogen electrode). The direct methanol fuel cells employing Fe-N-C as the cathodic catalyst displayed promising performance with a maximum power density of 33 mW/cm2 in alkaline media and 47 mW/cm2 in acidic media. The detailed investigation on the composition–structure–performance relationship by X-ray diffraction, X-ray photoelectron spectroscopy and Mössbauer spectroscopy suggests that Fe-N4, together with graphitic-N and pyridinic-N are the active ORR components. The promising direct methanol fuel cell performance displayed by the Fe-N-C catalyst is related to the intrinsic high catalytic activity, and critically for this application, to the high methanol tolerance.

Graphical AbstractA highly dispersed Fe-N-C electrocatalyst, prepared via a two-step pyrolysis synthesis route, exhibits promising ORR activity. The Fe-N-C cathode DMFC possesses high catalytic activity together with excellent methanol tolerance properties and shows promising discharging performance.Figure optionsDownload as PowerPoint slide