Pyrolysis of Iron–Vitamin B9 As a Potential Nonprecious Metal Electrocatalyst for Oxygen Reduction Reaction

This study presents the performance of a carbon-black-supported pyrolyzed vitamin B9 (folic acid)-treated cathode catalyst (py-Fe-FA/C) in the oxygen reduction reaction (ORR) and proton exchange membrane fuel cell (PEMFC). Electrochemical ORR measurements revealed that using py-Fe-FA/C resulted in excellent ORR activity through the direct four-electron reduction pathway. The H₂–O₂ PEMFC with py-Fe-FA/C in the cathodic side produces a maximum power density of 330 mW cm^–2 with the 80 °C operation temperature and the 1 atm back pressure. X-ray photoelectron spectroscopy and <i>in situ</i> X-ray adsorption spectroscopy proved that the enhanced ORR activity was caused by the network structure of polyaromatic hydrocarbons, quaternary-type (graphitic) nitrogen, and the coordination structure of the py-Fe-FA/C, as confirmed by the ORR mechanism study using detailed XPS and <i>in situ</i> X-ray adsorption spectroscopy. Particularly, <i>in situ</i> X-ray adsorption spectroscopy elucidated the ORR mechanism of the py-Fe-FA/C