“Engineering the Lewis Acidity of Fe Single-Atom Sites via Atomic-Level Tuning of Spatial Coordination Configuration for Enhanced Oxygen Reduction” (2025), by Qingyun Qu et al. Energy research paper. Original abstract below, unchanged. No free PDF was found.

Engineering the Lewis Acidity of Fe Single-Atom Sites via Atomic-Level Tuning of Spatial Coordination Configuration for Enhanced Oxygen Reduction

Qingyun Qu, Yu Mao, Shufang Ji et al. · February 17, 2025 · Energy

Abstract

Nitrogen-doped carbon-supported Fe catalysts (Fe-N-C) with Fe-N 4 active sites hold great promise for the oxygen reduction reaction (ORR). However, fine-tuning the structure of Fe-N 4 active sites to enhance their performance remains a grand challenge. Herein, we report an innovative design strategy to promote the ORR activity and kinetics of Fe-N 4 sites by engineering their Lewis acidity, which is achieved by tuning the spatial Fe coordination geometry. Theoretical calculations indicated that Fe 1 -N 4 SO 2 sites (with an axial –SO 2 group bonded to Fe) offered favorable Lewis acidity for the ORR, leading to optimized adsorption energies for the key ORR intermediates. To implement this strategy, we developed a molecular-cage-encapsulated coordination strategy to synthesize a Fe single-atom site catalyst (SAC) with Fe 1 -N 4 SO 2 sites. In agreement with theory, the Fe 1 -N 4 SO 2 /NC catalyst demonstrated outstanding ORR performance in both alkaline ( E 1/2 = 0.910 V in 0.1 M KOH) and acidic media ( E 1/2 = 0.772 V in 0.1 M HClO 4 ), surpassing commercial Pt/C and traditional Fe SACs with Fe 1 -N 4 sites or planar S-coordinated Fe 1 -N 4 -S sites. Moreover, this newly developed catalyst showed great application potential in quasi-solid-state Zn–air batteries, delivering superior performance across a wide temperature range.

Source page DOI: 10.1021/jacs.4c17444