The strain induced synergistic catalysis of FeN4 and MnN3 dual-site catalysts for oxygen reduction in proton- /anion- exchange membrane fuel cells

The Fe-N-C single-atom catalysts (SACs) have been widely explored for oxygen reduction reaction (ORR) in fuel cells. However, how to improve the ORR activity by tailoring the electronic structure of Fe-N-C catalysts is challenging. Herein, we synthesize a Fe-Mn-N-C dual-atom catalyst (DAC) with new local structure of FeN4-MnN3 moiety, and it exhibits ultralow H2O2 yield and better ORR performance than Fe-N-C and Mn-N-C SACs. Importantly, the Fe-Mn-N-C-based proton-/anion- exchange membrane fuel cells present ultrahigh power densities of 1.048 W cm−2 and 1.321 W cm−2, respectively. DFT results reveal that the strain yielded by the formation of Mn-Fe bond significantly optimizes the electronic structure of the Fe-Mn-N-C, and the co-adsorption of the Fe-Mn dual-sites for *OOH not only almost completely suppresses the 2e- ORR, but also breaks the linear correlation between GOH* and GOOH* proposed by Norskov et al., which provides a new route for the design of dual- site catalysts.