Although significant progress is achieved for the synthesis of noble metal-based nanocrystals (NCs), the construction of nanostructures with switchable dimensionality is not reported yet. Herein, a facile and general approach for the synthesis of multimetallic (PtCuPb and PtAgPb) NCs with dimensional-switching properties by manipulating the reduction rate involved in the growth of 2D nanosheets (2D-NS) and 1D nanowires (1D-NW) is presented. At a slow reduction rate, PtCuPb and PtAgPb NCs grow to form 2D-NS, in contrast, at a fast reduction rate, dimensionality alteration occurs to form 1D-NW. This 2D-NS to 1D-NW transition generates compressive surface strain in PtCuPb-NW with unique intermetallic core, active surface composition and exposes facet to boost oxygen reduction reaction (ORR). In PtCuPb-NW, compressive strain shifting the d-band electronic structure of platinum and weakening chemisorption of oxygenated species are shown. In detail, PtCuPb-NW/C exhibits superior specific and mass activities (4.91 mA cm⁻² and 2.65 A mgPt⁻¹) for ORR that are ≈19 and ≈15 times higher than the commercial Pt/C. The observations made and chemical principles unveiled in this effort indicate that a general approach exists for dimensional-switching and show a new class of Pt-based electrocatalysts with enhanced performance for fuel cells.

中文翻译：

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通过还原动力学控制三元合金的尺寸变换

尽管贵金属基纳米晶体（NCs）的合成取得了重大进展，但尚未报道构建具有可切换维度的纳米结构。在此，提出了一种通过控制二维纳米片 (2D-NS) 和一维纳米线 (1D-NW) 生长中涉及的还原率来合成具有尺寸转换特性的多金属 (PtCuPb 和 PtAgPb) NCs 的简便通用方法。 . 在缓慢的还原速率下，PtCuPb 和 PtAgPb NCs 生长形成 2D-NS，相反，在快速还原速率下，发生维度变化以形成 1D-NW。这种 2D-NS 到 1D-NW 的转变在 PtCuPb-NW 中产生压缩表面应变，具有独特的金属间化合物核、活性表面成分和暴露小平面以促进氧还原反应 (ORR)。在 PtCuPb-NW 中，显示了压缩应变改变了铂的 d 带电子结构并削弱了氧化物质的化学吸附。具体来说，PtCuPb-NW/C 表现出优异的比活度和质量活度（4.91 mA cm^-2和 2.65 A mgPt ^-1），ORR 比商业 Pt/C 高 ≈19 和 ≈15 倍。在这项工作中所做的观察和揭示的化学原理表明，存在一种用于尺寸转换的通用方法，并展示了一类新的 Pt 基电催化剂，具有增强的燃料电池性能。