Island‐in‐Sea Structured Pt3Fe Nanoparticles‐in‐Fe Single Atoms Loaded in Carbon Materials as Superior Electrocatalysts toward Alkaline HER and Acidic ORR

Abstract In this work, Pt 3 Fe nanoparticles (Pt 3 Fe NPs) with the ordered internal structure and Pt‐rich shells surrounded by plenty of Fe single atoms (Fe SAs) as active species (Pt 3 Fe NP‐in‐Fe SA) loaded in the carbon materials are successfully fabricated, which are abbreviated as island‐in‐sea structured (IISS) Pt 3 Fe NP‐in‐Fe SA catalysts. Moreover, the synergistic effect of O‐bridging between Pt 3 Fe NPs and Fe SAs, and the ordered internal structured Pt 3 Fe NPs with Pt‐rich shells of an optimal thickness contributes to the achievement of the local acidic environments on the surfaces of Pt 3 Fe NPs in the alkaline hydrogen evolution reaction (HER) and the enhancement of the desorption rate of *OH intermediate in the acidic oxygen reduction reaction (ORR). In addition, the electronic interactions between Pt 3 Fe NPs and dispersed Fe SAs cannot only provide efficient electrons transfer, but also prevent the aggregation and dissolution of Pt 3 Fe NPs. Furthermore, the overpotential and the half wave potential of the as‐prepared IISS Pt 3 Fe NP‐in‐Fe SA catalysts toward the alkaline HER and toward the acidic ORR are 8 mV at a current density of 10 mA cm −2 and 0.933 V, respectively, which is 29 lower and 86 mV higher than those (37 mV and 0.847 V) of commercial Pt/C catalysts.