Efficient Proton-exchange Membrane Fuel Cell Performance of Atomic Fe Sites via p-d Hybridization with Al Dopants.

ABSTRACT

Orbital hybridization to regulate the electronic structures and surface chemisorption properties of transition metals is of great importance for boosting the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells (PEMFCs). Herein, we developed a core-shell rambutan-like nanocarbon catalyst (FeAl-RNC) with atomically dispersed Fe-Al atom pairs from metal-organic framework (MOF) material. Experimental and theoretical results demonstrate that the strong p-d orbital hybridization between Al and Fe results in an asymmetric electron distribution with moderate adsorption strength of oxygen intermediates, rendering enhanced intrinsic ORR activity. Additionally, the core-shell rambutan-like structure of FeAl-RNC with abundant micropores and macropores can enhance the density of active sites, stability, and transport pathways in PEMFC. The FeAl-RNC-based PEMFC achieves excellent activity (68.4 mA cm-2 at 0.9 V), high peak power (1.05 W cm-2), and good stability with only 7% current loss after 100 h at 0.7 V under H2-O2 condition.