Fabrication of the PdAu Surface Alloy on an Ordered Intermetallic Au₃Cu Core for Direct H₂O₂ Synthesis at Ambient Pressure

Abstract

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 H2O2 selectivity and productivity were determined to be 94.8% and 7600 mmol H2O2 gPd –1·h–1 for the Au3Cu@AuPd0.25 catalyst 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 O2 activation and formation of the key OOH intermediate, are considered as the active sites for H2O2 synthesis. This strategy for the fabrication of the surface Pd–Au alloy can not only improve the selectivity and productivity of H2O2 but also improve the utilization rate of Pd atoms.

Deposition of Pd, Pt, and PdPt Nanoparticles on TiO2 Powder Using Supercritical Fluid Reactive Deposition: Application in the Direct Synthesis of H2O2

“…H 2 O 2 is increasingly gaining significance as a so-called green oxidizing agent. Being highly active, H 2 O 2 is receiving more and more attention in sectors such as the paper and pulp industries or waste water treatment [14][15][16]. Recently, due to the COVID-19 pandemic, H 2 O 2 has been gaining relevance in disinfection applications, such as the reprocessing of clinical masks [17,18].…”