Fabrication of the PdAu Surface Alloy on an Ordered Intermetallic Au3Cu Core for Direct H2O2 Synthesis at Ambient Pressure
Fabrication of the PdAu Surface Alloy on an Ordered Intermetallic Au3Cu Core for Direct H2O2 Synthesis at Ambient Pressure
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DOI：
10.1021/acs.iecr.2c01482
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发表时间：
2022-08
期刊：
影响因子：
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通讯作者：
Lian-Jie Fu;Shijie Liu;Yanbo Deng;Huaqiang He;Shaojun Yuan;Like Ouyang
中科院分区：
文献类型：
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作者：
Lian-Jie Fu;Shijie Liu;Yanbo Deng;Huaqiang He;Shaojun Yuan;Like Ouyang
在氢气和氧气直接合成过氧化氢的反应中，钯金合金催化剂由于其优异的活性、选择性和稳定性而得到了广泛的研究。然而，对于Pd-Au块体合金催化剂，由于Pd原子难以暴露，Pd的原子利用效率仍然较低。表面Pd-Au合金的构建为提高Pd的原子利用效率提供了一种潜在的策略。然而，如何合理设计和可控制备既具有高分散度又具有高密度Pd位的Pd-Au表面合金仍然是一个巨大的挑战。本文利用Au 3Cu纳米粒子的有序结构和Pd原子对Cu原子的简单电偶置换，成功制备了Au3Cu@AuPd核壳催化剂。X射线衍射、透射电子显微镜和原位漫反射红外傅里叶变换光谱表征表明Au 3Cu和Au3Cu@AuPd中存在有序结构，Pd原子在表面高度分散。在283 K和常压下，Au3Cu@AuPd0.25催化剂的H2 O2选择性和产率分别为94.8%和7600 mmol H2 O2 gPd-1·h-1。该催化剂的优异性能主要来源于表面Pd-Au合金与有序Au 3Cu核的几何效应。催化剂表面大量的高分散的Pd原子被Au原子包围，对O2的不解离活化和关键OOH中间体的形成具有高的选择性，被认为是H2 O2合成的活性位.这种表面Pd-Au合金的制备策略不仅可以提高H2 O2的选择性和产率，而且可以提高Pd原子的利用率。
In the direct synthesis of hydrogen peroxide from hydrogen and oxygen, Pd–Au alloy catalysts have been widely studied due to their excellent activity, selectivity, and stability. However, for the Pd–Au bulk alloy catalyst, the atomic utilization efficiency of Pd is still low due to the difficulty of exposure of Pd atoms. Construction of the surface Pd–Au alloy provides a potential strategy to enhance the atomic utilization efficiency of Pd. However, the rational design and controllable preparation of the Pd–Au surface alloy with both high dispersion and high density of Pd sites still remains a great challenge. Here, by using the ordered structure of Au3Cu nanoparticles and the facile galvanic replacement of Cu atoms by Pd atoms, the Au3Cu@AuPd core–shell catalysts were successfully prepared. X-ray diffraction, transmission electron microscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy characterizations demonstrated the existence of ordered structure in Au3Cu and Au3Cu@AuPd and high dispersion of Pd atoms on the surface. The H2O2selectivity and productivity were determined to be 94.8% and 7600 mmol H2O2gPd–1·h–1for the Au3Cu@AuPd0.25catalyst at 283 K under ambient pressure, respectively. The excellent performance of the catalyst is mainly originated from the geometric effect of the surface Pd–Au alloy with an ordered Au3Cu core. The abundant highly dispersed Pd atoms surrounded by Au atoms on the catalyst surface, which have high selectivity for non-dissociation of O2activation and formation of the key OOH intermediate, are considered as the active sites for H2O2synthesis. This strategy for the fabrication of the surface Pd–Au alloy can not only improve the selectivity and productivity of H2O2but also improve the utilization rate of Pd atoms.