Surface Diels-Alder adducts on multilayer graphene for the generation of edge-enriched single-atom FeN4 sites for ORR and OER electrocatalysis

The assembly of atomically dispersed iron-nitrogen (FeN4) sites into graphitic structures is a promising approach for sustainable production of bifunctional electrocatalysts for the oxygen electroreduction (ORR) and oxygen evolution (OER) reactions. In addition, single-atom FeN4 sites at the edges of carbon substrates provide higher electrocatalytic performance than those in plane. Unfortunately, the conventional high-temperature pyrolysis method does not allow the generation of edge-enriched FeN4 single-atom sites. Herein, a novel low-temperature and solvent-free mechanochemical synthesis based on the use of dipyridylpyridazine (dppz) functionalized multilayer graphene as a starting material is proposed for precisely engineered location of these FeN4 active sites at the edges. After careful characterization of these dppz-based materials, the ORR and OER electrocatalytic performance was investigated, demonstrating the efficient formation of FeN4 sites at the edges as well as their excellent bifunctional behavior for the ORR and OER. This work paves the way for the development of sustainable approaches for the generation of edge-enriched FeN4 single atom sites on multilayer graphene structures.