High-performance anion exchange membrane fuel cells and zinc–air batteries enabled by a hierarchically porous hollow Fe/N/C aerogel catalyst

Abstract

Currently, the development of Fe/N/C catalysts is attracting more and more attention, due to their exciting potential applications in advanced anion-exchange membrane fuel cells (AEMFCs) and zinc–air batteries (ZABs). Among these, the main hurdle lies in the high mass transport resistance associated with the micropore-dominated Fe/N/C catalysts. In this work, we report the exploration of a carboxymethyl cellulose (CMC)-induced hierarchically porous hollow Fe/N/C aerogel (FeN-CA) catalyst, which remarkably enhances mass transport and improves the AEMFC/ZAB performance. It is witnessed that the resulting aerogel catalyst increases the mesoporous and macroporous structures, thus effectively reducing the oxygen transport resistance within the electrodes at high current densities. Consequently, the resulting FeN-CA catalyst in AEMFCs exhibits a reduced mass transfer overpotential (235 mV) at 1500 mA cm⁻² and a peak power density of 774 mW cm⁻² at 1724 mA cm⁻², respectively. Moreover, in ZABs, it delivers an exceptional peak power density of up to 500 mW g_catalyst⁻¹ (25 °C) and 766 mW g_catalyst⁻¹ (80 °C), which is the highest among non-precious metal catalysts (NPMCs) ever reported, indicating their future potential in commercial applications.