The catalytic performance of metal nanoparticles is often affected by surface oxidation levels. Instead of post-synthesis oxidation/reduction, we propose an efficient method to modulate the oxidation levels by tuning the composition of bimetallic nanoparticles. Here we report a series of Pt–Re bimetallic nanoparticles synthesized via a facile thermal co-reduction process, with a uniform size of approximately 3 nm. The investigation of the growth of the Pt–Re nanoparticles suggests that the Re atoms were enriched on the surface, as confirmed by X-ray photoelectron spectroscopy. Furthermore, X-ray absorption spectroscopy showed that metallic Re was decreased and high-valency ReO_x species were increased in particles with higher Re/Pt ratios. In the etherification of allylic alcohols catalyzed by Pt–Re nanoparticles of different compositions under ambient conditions, particles with higher Re/Pt ratios exhibited significantly better performances. The highest mass activity of Pt–Re bimetallic nanoparticles (127 μmol·g⁻¹·s⁻¹) was more than forty times that of the industrial catalyst CH₃ReO₃ (3 μmol·g⁻¹·s⁻¹). The catalytically active sites were associated with ReO_x and could be tuned by adjusting the Pt ratio.

Open image in new window

金属纳米颗粒的催化性能通常受表面氧化水平的影响。代替合成后的氧化/还原，我们提出了一种通过调节双金属纳米颗粒的组成来调节氧化水平的有效方法。在这里，我们报告了一系列通过简便的热共还原过程合成的Pt-Re双金属纳米颗粒，其均匀大小约为3 nm。通过X射线光电子能谱证实，对Pt-Re纳米颗粒生长的研究表明Re原子在表面富集。此外，X射线吸收光谱显示金属Re降低，高价ReO _x具有较高Re / Pt比的颗粒中的物种增加了。在环境条件下，由不同组成的Pt-Re纳米粒子催化的烯丙醇醚化反应中，具有较高Re / Pt比的粒子表现出明显更好的性能。Pt-Re双金属纳米颗粒的最高质量活性（127μmol·g ^-1 ·s ^-1）是工业催化剂CH ₃ ReO ₃（3μmol·g ^-1 ·s ^-1）的四十倍以上。催化活性位点与ReO _x有关，可以通过调节Pt比例进行调节。

在新窗口中打开图像