Direct methanol fuel cells (DMFCs) hold great promise as clean energy conversion devices in the future. Noble metal nanocatalysts, renowned for their exceptional catalytic activity and stability, play a crucial role in DMFCs. Among these catalysts, Pt- and Pd-based nanocatalysts are widely recognized as the most effective catalysts for the electrochemical methanol oxidation reaction (MOR), which is the key half-cell reaction in DMFCs. However, due to the high cost of Pt- and Pd-based materials, there is a strong desire to further enhance their catalytic performance. One of the most promising approaches for it is to develop noble metal-based alloy nanocatalysts, which have shown great potential in improving electrocatalytic activity. Notably, advancements in phase engineering of nanomaterials (PEN) have revealed that noble metal-based nanomaterials with unconventional phases exhibit superior catalytic properties in various catalytic reactions compared to their counterparts with conventional phases. To obtain noble metal-based nanocatalysts with unconventional crystal phases, wet-chemical epitaxial growth has been employed as a facile and effective method, utilizing unconventional-phase noble metal nanocrystals as templates. Nevertheless, epitaxially growing bimetallic alloy nanostructures with unconventional crystal phases remains a challenge, impeding further exploration of their catalytic performance in electrochemical reactions such as MOR. In this study, we utilize 4H hexagonal phase Au (4H-Au) nanoribbons as templates for the epitaxial growth of unconventional 4H hexagonal PdFe, PdIr, and PdRu, resulting in the formation of 4H-Au@PdM (M = Fe, Ir, and Ru) core-shell nanoribbons. As a proof-of-concept application, we investigate the electrocatalytic activity of the synthesized 4H-Au@PdFe nanoribbons towards MOR, which exhibit a mass activity of 3.69 A·mg_Pd⁻¹, i.e., 10.5 and 2.4 times that of Pd black and Pt/C, respectively, placing it among the best Pd- and Pt-based MOR electrocatalysts. Our strategy opens up an avenue for the rational construction of unconventional-phase multimetallic nanostructures to explore their phase-dependent properties in various applications. © Editorial office of Acta Physico-Chimica Sinica.

Pd基合金納米材料通常具有傳統的面心立方(fcc)晶相。本文以密排六方4H相Au(4H-Au)納米帶為範本,外延生長非常規4H晶相的PdFe、PdIr和PdRu,形成4H-Au@PdM (M=Fe、Ir和Ru)核殼合金納米帶。合成的4H-Au@PdFe納米帶被用於鹼性環境中甲醇電催化氧化反應(MOR)的催化劑,表現出優越的品質活性(3.69 A·mg_Pd^-1),分別為Pt/C和Pd黑催化劑質量活性的2.4和10.5倍,也躋身於最好的Pd基和Pt基MOR電催化劑之列。這一策略為合理設計和可控合成具有非常規晶相的多金屬納米結構提供了策略,從而為深入研究多金屬納米結構晶相依賴的性質和應用提供了可能。© Editorial office of Acta Physico-Chimica Sinica.