Enhanced electronic interaction between iron phthalocyanine and cobalt single atoms promoting oxygen reduction in alkaline and neutral aluminum-air batteries

Abstract

Aluminum-air batteries (AABs) have received increasing interest for next-generation energy conversion systems. However, the development of AABs is hindered by the sluggish kinetics of cathodic oxygen reduction reaction (ORR). Iron phthalocyanine (FePc) is one of the active electrocatalysts for ORR but still far from Pt-based materials in terms of electrocatalytic performance. Herein, FePc molecules anchored on the Co single atoms/N-doped porous carbon nanofibers (denoted as FePc@Co-SAs/PCNF) with enhanced electronic interaction are prepared for the ORR. X-ray absorption spectra (XAS) analysis confirms the atomically dispersed Fe and Co sites and reveals the electronic interaction between FePc and Co-N3. The cobalt single atoms can break the electronic distribution symmetry of FePc and induce electronic localization to boost the ORR performance. As a result, the FePc@Co-SAs/PCNF electrocatalyst demonstrates a remarkable ORR activity in both alkaline and neutral electrolytes. The electrocatalytic ORR processes on the FePc@Co-SAs/PCNF are recorded by in-situ Raman spectra. Moreover, the ORR mechanism is discussed, which is supported by density functional theory (DFT) calculations. Furthermore, the AABs based on FePc@Co-SAs/PCNF exhibit remarkable discharge performance. This study offers a new strategy for rationally designing metallic macrocyclic compound electrocatalysts and promotes the development of metal-air batteries.