Surface segregation technique is a valid method to promote the alkaline hydrogen evolution reaction (HER) activities of bimetallic PtNi alloys. In this work, a novel tactic was proposed to induce the in-situ Pt segregation in Pt@Pt5Ni4 nanowires using H2 acted as a structure-directing reagent, leading to the formation of Pt@PtNi@Pt core–shell nanowires, with the optimal H2 pressure being 0.1 MPa. Thermodynamically, H2 can adjust the surface layer by altering the metal surface free energy. Kinetically, H2 significantly affects the reduction kinetics of metal precursors, resulting in a higher reduction rate of Ni2+ than Pt2+, promoting Pt surface segregation and transforming Pt@Pt5Ni4 nanowires into Pt@PtNi@Pt nanowires. The Pt@PtNi@Pt catalyst demonstrated an exceedingly low overpotential of 15.6 mV (10 mA cm−2) and Tafel slope of 35.6 mV dec-1, closely related to the Pt shell induced by H2. Density functional theory simulations indicated that the generation of the Pt@PtNi@Pt core–shell structure resulted in a downward shift of the d-band center of Pt, resulting in a ΔGH* of only −0.03 eV.

中文翻译：

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H2 诱导的 Pt 分离构建了促进析氢的 Pt@PtNi@Pt 纳米线


表面偏析技术是促进双金属 PtNi 合金碱性析氢反应 （HER） 活性的有效方法。在这项工作中，提出了一种新的策略，使用 H2 作为结构导向试剂在Pt@Pt5Ni4纳米线中诱导原位 Pt 分离，从而形成Pt@PtNi@Pt核壳纳米线，最佳 H2 压力为 0.1 MPa。在热力学上，H2 可以通过改变金属表面自由能来调整表面层。在动力学上，H2 显着影响金属前驱体的还原动力学，导致 Ni2+ 的还原速率高于 Pt2+，促进 Pt 表面偏析并将 Pt@Pt5Ni4 纳米线转化为Pt@PtNi@Pt纳米线。Pt@PtNi@Pt催化剂表现出 15.6 mV （10 mA cm-2） 的极低过电位和 35.6 mV dec-1 的塔菲尔斜率，与 H2 诱导的 Pt 壳密切相关。密度泛函理论模拟表明，Pt@PtNi@Pt核壳结构的产生导致 Pt 的 d 波段中心向下移动，导致 ΔGH* 仅为 −0.03 eV。