Controlling the Distribution of Metal Elements in Core@Shell Nanosheets for Highly Efficient Direct Formic Acid Electrooxidation

Synthesizing two-dimensional (2D) platinum-based nanomaterials with controlled phases and compositions remains a formidable challenge. Here, we report PtTe2Bi@PtxBi hexagonal core@shell nanosheets (PtTe2Bi@PtxBi HCSNSs, x = 2, 3, 4) for an efficient formic acid oxidation reaction (FAOR). Precise structure analysis unveils the atomic layer arrangements of trigonal and cubic phases for core and shell parts in PtTe2Bi@Pt3Bi HCSNSs, finding the enrichments of Te, Bi, and Pt in the core, second outer layer, and outermost layer, respectively. They exhibit the specific and mass activities of 9.9 mA cm-2 and 6.1 A mgPt-1, 52.1 and 46.9 times higher than those of commercial Pt/C. The membrane electrode assembly (MEA) power density of 169.6 mW cm-2 and much enhanced stability can be realized. The dehydrogenation pathway is more favorable on their surface, and the high energy barrier to produce CO and relatively weak binding with CO jointly contribute to their superior CO tolerance.