Single Fe atoms anchored by short-range ordered nanographene boost oxygen reduction reaction in acidic media

The development of efficient and stable single-atom electrocatalysts with earth-abundant metals have emerged as a promising alternative to the costly Pt-based nanomaterials for oxygen reduction reaction (ORR). Herein, we synthesize a highly efficient electrocatalyst with single Fe atoms anchored by N-doped short-range ordered carbon loading on 2 D reduced graphene oxide (RGO). Unlike the highly graphitized carbon materials in previous ORR catalysts, in which the diffusion of oxygen molecules (∼3.46 A) are blocked by long carbon chains and small interlayer spacing (∼3.4 A), it is found that the Fe/N-doped nanographene possesses large interlayer spacing (>4 A) and short carbon fragments in one layer. The unique nanographene structure in nanoscale can facilitate the transport of oxygen molecules to the active sites of atomically dispersed FeN4 and FeN5. In acidic media for ORR, as-prepared Fe1-N-NG/RGO catalyst exhibited half-wave potential (E1/2) of 0.84 V versus the reversible hydrogen electrode, and the loss of E1/2 is less than 5 mV during 15,000 potential cycles.