Regulating the FeN4 Moiety by Constructing Fe–Mo Dual-Metal Atom Sites for Efficient Electrochemical Oxygen Reduction

An Fe–N–C catalyst with an FeN4 active moiety has gained ever-increasing attention for the oxygen reduction reaction (ORR); however, the catalytic performance is sluggish in acidic solutions and the regulation is still a challenge. Herein, Fe–Mo dual-metal sites were constructed to tune the ORR activity of a mononuclear Fe site embedded in porous nitrogen-doped carbon. The cracking of O–O bonds is much more facile on the Fe–Mo atomic pair site due to the preferred bridge-cis adsorption model of oxygen molecules. The downshift of the Fe d band center when an Mo atom is introduced to the FeN x configuration optimizes the absorption–desorption behavior of ORR intermediates in the FeMoN6 active moiety, thus boosting the catalytic performance. The construction of dual-metal atom sites to regulate the catalytically active moiety paves the way for boosting the electrocatalytic performance of other similar non-precious-metal catalysts.