In this paper, a new galvanic displacement reduction (GDR) approach was demonstrated for Au–PtNPs synthesis with different Pt : Au compositions in an aqueous medium. PtNPs were initially synthesized by the reduction of H₂PtCl₆ using trisodium citrate and sodium borohydride. Addition of various concentrations of HAuCl₄ to PtNPs leads to the formation of Au–PtNPs, which follows the GDR between Pt(0) and AuCl₄⁻ ions. The formation of Au–PtNPs was monitored by UV-vis spectroscopy by tuning the mole ratio of Pt : Au. HR-TEM images showed that the Au–PtNPs were spherical with 11 nm diameter. HR-TEM, XRD and XPS analysis showed that the formed Au–PtNPs were in the form of a core–shell structure. The colloidal Au–PtNPs were then attached on a glassy carbon (GC) electrode via a 1,6-hexanediamine linker for the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). The attachment of Au–PtNPs was further confirmed by XRD, line scanning coupled with energy-dispersive X-ray spectroscopy (EDS) and cyclic voltammetry (CV). The Au–PtNPs modified electrode exhibits a higher heterogeneous electron transfer rate constant of 4.12 × 10⁻³ cm s⁻¹ than bare (1.01 × 10⁻⁴ cm s⁻¹) and PtNP (1.77 × 10⁻⁴ cm s⁻¹) modified GC electrodes. Further, the Au–PtNPs modified electrode exhibited a composition dependent activity towards the MOR and ORR. It was found that the modified electrode with a Pt : Au ratio of 1 : 0.09 shows 8 times more sensitive oxidation for the MOR when compared to a commercial Pt/C catalyst. The present Au–PtNPs catalyst exhibits a greatly enhanced catalytic activity in terms of mass activity (132 mA mg Pt⁻¹) and excellent stability relative to the commercial Pt/C catalyst.

中文翻译：

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减少位移的Au-Pt双金属纳米颗粒：一种用于甲醇氧化和氧还原的高度耐用的电催化剂†

在本文中，展示了一种在水介质中具有不同Pt：Au组成的Au-PtNPs合成的新的电流位移减少（GDR）方法。最初通过使用柠檬酸三钠和硼氢化钠还原H ₂ PtCl ₆来合成PtNP 。在PtNPs中添加各种浓度的HAuCl ₄会导致Au–PtNPs的形成，其遵循Pt（0）和AuCl ₄ ⁻之间的GDR离子。通过调节Pt：Au的摩尔比，通过紫外-可见光谱法监测Au-PtNPs的形成。HR-TEM图像显示Au-PtNPs是球形的，直径为11 nm。HR-TEM，XRD和XPS分析表明，形成的Au-PtNPs为核-壳结构形式。然后将胶体Au–PtNPs通过1，6-己二胺连接剂附着在玻璃碳（GC）电极上，以进行甲醇氧化反应（MOR）和氧还原反应（ORR）。XRD，线扫描，能量色散X射线光谱法（EDS）和循环伏安法（CV）进一步证实了Au-PtNPs的附着。Au-PtNPs修饰电极比裸露电极（1.01×10）表现出更高的异质电子传递速率常数，为4.12×10 ^-3 cm s ^-1-4 cm s ^-1）和PtNP（1.77×10 ^-4 cm s ^-1）修饰的GC电极。此外，Au-PtNPs修饰电极对MOR和ORR表现出依赖成分的活性。已经发现，与市售的Pt / C催化剂相比，Pt∶Au比率为1∶0.09的改性电极对MOR显示出8倍的MOR敏感氧化。相对于商业化的Pt / C催化剂，目前的Au-PtNPs催化剂在质量活性（132 mA mg Pt ^-1）方面显示出大大增强的催化活性。