Biological Neural Network-Inspired Micro/Nano-Fibrous Carbon Aerogel for Coupling Fe Atomic Clusters With Fe-N4 Single Atoms to Enhance Oxygen Reduction Reaction

Abstract

Nitrogen-coordinated metal single atoms catalysts, especially with M-N₄ configuration confined within the carbon matrix, emerge as a frontier of electrocatalytic research for enhancing the sluggish kinetics of oxygen reduction reaction (ORR). Nevertheless, due to the highly planar D_4h symmetry configuration in M-N₄, their adsorption behavior toward oxygen intermediates is limited, undesirably elevating the energy barriers associated with ORR. Moreover, the structural engineering of the carbon substrate also poses significant challenges. Herein, inspired by the biological neural network (BNN), a reticular nervous system for high-speed signal processing and transmitting, a comprehensive structural biomimetic strategy is proposed for tailoring Fe-N₄ single atoms (Fe SAs) coupled with Fe atomic clusters (Fe ACs) active sites, which are anchored onto chitosan microfibers/nanofibers-based carbon aerogel (CMNCA-Fe_SA+AC) with continuous conductive channels and an oriented porous architecture. Theoretical analysis reveals the synergistic effect of Fe SAs and Fe ACs for optimizing their electronic structures and expediting the ORR. The ingenious biomimetic strategy will shed light on the topology engineering and structural optimization of efficient electrocatalysts for advanced electrochemical energy conversion devices.