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, Pt3Fe nanoparticles (Pt3Fe NPs) with the ordered internal structure and Pt‐rich shells surrounded by plenty of Fe single atoms (Fe SAs) as active species (Pt3Fe NP‐in‐Fe SA) loaded in the carbon materials are successfully fabricated, which are abbreviated as island‐in‐sea structured (IISS) Pt3Fe NP‐in‐Fe SA catalysts. Moreover, the synergistic effect of O‐bridging between Pt3Fe NPs and Fe SAs, and the ordered internal structured Pt3Fe NPs with Pt‐rich shells of an optimal thickness contributes to the achievement of the local acidic environments on the surfaces of Pt3Fe 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 Pt3Fe NPs and dispersed Fe SAs cannot only provide efficient electrons transfer, but also prevent the aggregation and dissolution of Pt3Fe NPs. Furthermore, the overpotential and the half wave potential of the as‐prepared IISS Pt3Fe 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.

Gas–Solid Reaction Synthesis and Electrocatalytic Oxygen Reduction of Pt-Skin L10-PtFe/C

“…The ordered Pt-based intermetallic compounds (Pt-IMCs) have rapidly attracted growing research interest in the ORR field due to their unique electronic, geometric, steric, and ordering effects in the past 10 years. − The introduction of transition-metal atoms could cause lattice strain of Pt on the Pt-IMCs surface change the electronic structure and d-band center of Pt and improve the ORR catalytic activity and cycle stability of Pt-IMCs. − Furthermore, it is generally believed that downsizing could effectively improve the electrocatalytic activity of nanomaterials. , However, synthesizing highly ordered Pt-IMCs requires typically high energy to achieve atom arrangement from disorder to order, which inevitably causes aggregation and growth of nanoparticles. Hence, how to prepare highly ordered, small-sized Pt-IMCs is a great challenge. , …”