A DFT Study on the Activity of FeMN6C Dual-Atom Catalysts for Oxygen Reduction Reaction

Abstract

The low-cost and highly active FeN₄C single-atom catalyst is currently one of the most promising oxygen reduction catalysts for replacing the precious metal catalysts in fuel cells. The electron occupation states of Fe 3d orbitals have been proved to play a determining role in the catalytic activity of FeN₄C. Herein, by adding the second transition-metal atom M to form FeMN₆C, we modulate the 3d-orbital splitting and spin states of Fe to uncover the spin effects on the adsorption energies of oxygen-containing intermediates and catalytic activity. The results reveal that the introduction of M gives rise to various electron occupation states and magnetic moments of the Fe atom, tuning the catalytic activity of FeN₄C. Among them, FeRhN₆C and FePdN₆C have low theoretical ORR overpotentials of 0.41 and 0.42 V. It is found that there is a volcano relation between the spin moments of Fe and the adsorption energies rather than the linear relation reported in other work.