Iron and Nitrogen Doped Hierarchical Porous Lignin-Derived Carbons as Oxygen Reduction Reaction Electrocatalysts

Abstract

Non-precious metal Fe-N-C electrocatalysts, which can be used as cathode materials for oxygen reduction reaction in an anion-exchange membrane fuel cell were synthesized and investigated by electrochemical and physicochemical methods. The carbon, iron, and nitrogen precursors used to synthesize the electrocatalysts were lignin, iron(II) acetate, and 1,10-phenanthroline, respectively. To obtain the hierarchical porous carbon support, lignin was carbonized using magnesium nitrate hexahydrate as template via high-temperature pyrolysis. Several pyrolysis temperatures (800-1100 °C) were employed to find the optimal carbonization temperature. Iron and nitrogen doping was performed for all carbon materials through flash pyrolysis at 800 °C. The electrocatalytic performance of the prepared Fe-N-C catalyst materials toward the oxygen reduction reaction was studied and compared using the rotating disk electrode method. The physicochemical properties of the catalyst materials were investigated by various analytical methods, namely scanning electron microscopy, scanning transmission electron microscopy, N2 physisorption, X-ray photoelectron spectroscopy, and Raman spectroscopy.