Boosting the Electrocatalytic Activity of Fe−Co Dual‐Atom Catalysts for Oxygen Reduction Reaction by Ligand‐Modification Engineering.

Development of high‐efficiency and low‐cost electrocatalysts as the platinum substitute for the oxygen reduction reaction (ORR) is of significance for electrochemical energy conversion and storage devices, such as fuel cells and rechargeable batteries. Here we report graphene‐based nitrogen‐coordinated Fe−Co dual‐atom catalysts (referred to as FeCoN6) with markedly enhanced ORR activity by ligand‐modification. By density functional theory calculations, we thoroughly investigated the ORR activity of three preferred FeCoN6 isomers (denoted as FeCoN6‐I, FeCoN6‐II, and FeCoN6‐III) and their complexes with the ligands of ORR intermediates such as *O, *OH, and *O2. Our results reveal that these ligands cause the apparent shift of d‐orbitals of metal atoms toward the Fermi level to modulate the adsorption strength for reaction intermediates, thereby significantly improving the ORR activity of FeCoN6 complexes. Notably, FeCoN6‐I(OH) and FeCoN6‐I(O2) with the lowest overpotential of ∼0.23 V possessed the best ORR activity, which are superior to pristine FeCoN6 and available Pt catalysts. These results not only build on the fundamental understanding of the catalytic mechanism of ligand modified dual‐atom catalysts but also provide a new strategy to develop highly efficient ORR electrocatalysts by ligand‐modification engineering. [ABSTRACT FROM AUTHOR]