Iron/Nitrogen/Phosphorus Co-Doped Three-Dimensional Porous Carbon as a Highly Efficient Electrocatalyst for Oxygen Reduction Reaction

Abstract

Developing low cost, high active and stable non noble electrocatalysts for oxygen reduction reaction (ORR) is of great importance for the practical application of proton exchange membrane fuel cells (PEMFCs). Herein, we develop a hydrogel-pyrolysis strategy to synthesize an active iron/nitrogen/phosphorous co-doped carbon electrocatalyst (denoted as PANI-Fe/PA-N1050) by adopting aniline, phytic acid and iron trichloride as the precursors. The catalytic behavior for ORR in 0.1M NaOH solution was examined by cyclic voltammetry (CV), linear scanning voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The results show that, compared with the single-doped counterparts, the iron/nitrogen/phosphorous co-doped carbon electrocatalyst exhibits a superior ORR performance in terms of an initial half-wave potential of 0.84 V vs. RHE and degradation of 14 mV after 1000 cycles. The performance enhancement could be attributed to the following aspects: (1) the crosslink of phytic acid and polyaniline forms a hydrogel, which after pyrolysis possesses high electrochemical surface area so that allows to accommodate quantity of active sites; (2) the Fe, N, P triple-doping generates abundant active sites including Fe-Nx, graphitic N and P-doped carbon; (3) the charge transfer resistance decreases benefiting from the continuous 3D porous structure of carbon. The iron/nitrogen/phosphorous co-doped 3D porous carbon materials prepared by the facile and scalable hydrogel-pyrolysis route is also promising for energy conversion/storage.