2H-Au Nanosheet-Templated Growth of PdFe for Electrocatalytic Methanol Oxidation

Pd-based alloy nanomaterials normally crystallize in the conventional face-centered cubic (fcc) crystal phase. Here, 2H-Au nanosheets (NSs), possessing 2H crystal phase (2H: hexagonal close-packed with a stacking sequence of “AB”), are used as templates for the growth of PdFe, during which the 2H-to-fcc phase transformation in Au NSs happens, leading to the formation of 2H/fcc Au@PdFe core–shell NSs. By changing the Pd/Fe atomic ratio, the 2H/fcc phase ratio in 2H/fcc Au@PdFe NSs can be tuned accordingly. As a proof-of-concept application, the as-synthesized 2H/fcc Au@Pd_0.66Fe_0.34 NSs are used as an electrocatalyst for methanol oxidation reaction (MOR) in alkaline media, exhibiting a remarkable mass activity of 4.39 A mg⁻¹_Pd, which is 1.7, 5.4 and 12.9 times that of 2H/fcc Au@Pd_0.56Fe_0.44 NSs (2.57 A mg⁻¹_Pd), 2H/fcc Au@Pd_0.40Fe_0.60 NSs (0.81 A mg⁻¹_Pd), and Pd black (0.34 A mg⁻¹_Pd), respectively, placing it among the best of reported Pd-based MOR electrocatalysts. This strategy, based on phase engineering of nanomaterials (PEN), paves an efficient way to the rational design and controlled synthesis of noble multimetallic nanostructures with unconventional phases for exploring the phase-dependent properties and applications. © 2024 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH.