Tuning Surface Structure of Pd(3)Pb/Pt(n)Pb Nanocrystals for Boosting the Methanol Oxidation Reaction

Developing an efficient Pt‐based electrocatalyst with well‐defined structures for the methanol oxidation reaction (MOR) is critical, however, still remains a challenge. Here, a one‐pot approach is reported for the synthesis of Pd(3)Pb/Pt(n)Pb nanocubes with tunable Pt composition varying from 3.50 to 2.37 and 2.07, serving as electrocatalysts toward MOR. Their MOR activities increase in a sequence of Pd(3)Pb/Pt(3.50)Pb << Pd(3)Pb/Pt(2.07)Pb < Pd(3)Pb/Pt(2.37)Pb, which are substantially higher than that of commercial Pt/C. Specifically, Pd(3)Pb/Pt(2.37)Pb electrocatalysts achieve the highest specific (13.68 mA cm(−2)) and mass (8.40 A mg(Pt) (−1)) activities, which are ≈8.8 and 6.8 times higher than those of commercial Pt/C, respectively. Structure characterizations show that Pd(3)Pb/Pt(2.37)Pb and Pd(3)Pb/Pt(2.07)Pb are dominated by hexagonal‐structured PtPb intermetallic phase on the surface, while the surface of Pd(3)Pb/Pt(3.50)Pb is mainly composed of face‐centered cubic (fcc)‐structured Pt(x)Pb phase. As such, hexagonal‐structured PtPb phase is much more active than the fcc‐structured Pt(x)Pb one toward MOR. This demonstration is supported by density functional theory calculations, where the hexagonal‐structured PtPb phase shows the lowest adsorption energy of CO. The decrease in CO adsorption energy and structural stability also endows Pd(3)Pb/Pt(n)Pb electrocatalysts with superior durability relative to commercial Pt/C.