Effect of Catalyst Pore Size on the Performance of Non-Precious Fe/N/C-Based Electrocatalysts for High-Temperature Polymer Electrolyte Membrane Fuel Cells

Abstract

Owing to the high cost of technologies utilizing the oxygen reduction reaction (ORR) in fuel cell applications, considerable efforts have been recently made to develop non-precious metal electrocatalysts for the commercialization of the low-temperature polymer electrolyte membrane fuel cells (LT-PEMFCs). By extension, non-precious-metal electrocatalysts can be a cost-effective solution for the commercialization of high-temperature PEMFCs (HT-PEMFCs). However, no previous reports have been published regarding the applicability. Herein, we demonstrate that a hierarchical mesoporous iron and nitrogen co-doped carbon (Fe/N/C) electrocatalyst is able to efficiently electrocatalyze the ORR in a phosphoric acid electrolyte with a half-wave potential of 0.72 V (only 170 mV deviation from conventional Pt/C) and high selectivity (electron-transfer number > 3.95) with a mild overpotential. Furthermore, we fabricated HT-PEMFC devices on the basis of hierarchical mesoporous Fe/N/C electrocatalysts and non-aqueous electrolytes, which exhibited a high performance, over 20 mW/cm (2). Besides, the optimal hierarchical porosity of the mesoporous Fe/N/C catalyst contributes to its high ORR activity. It is considered that it provides a large surface area for electrocatalytic ORR, and improves the proton and oxygen transport properties.