One pot microwave synthesis of highly stable AuPd@Pd supported core-shell nanoparticles

• Published in: Faraday discussions 2018-09, Vol.28, p.49-425
• Main Authors: Howe, Alexander G. R, Miedziak, Peter J, Morgan, David J, He, Qian, Strasser, Peter, Edwards, Jennifer K
• Format: Article
• Language: English
• Subjects: Bimetals; Catalysis; Catalysts; Chemical synthesis; Core-shell particles; Core-shell structure; Deactivation; Gold; Heat treatment; Hydrogen peroxide; Metal chlorides; Morphology; Nanoparticles; Palladium; Reduction; Reduction (metal working); Shell stability; Structural stability; Synergistic effect
• ISSN: 1359-6640; 1364-5498
• DOI: 10.1039/c8fd00004b

A series of 1 wt% supported Au, Pd and AuPd nanoalloy catalysts were prepared via microwave assisted reduction of PdCl 2 and HAuCl 4 in a facile, one pot process. The resulting materials showed excellent activity for the direct synthesis of hydrogen peroxide from hydrogen and oxygen, with a synergistic effect observed on the addition of Au into a Pd catalyst. Detailed electron microscopy showed that the bimetallic particles exhibited a core-shell morphology, with an Au core surrounded by an Au-Pd shell, with a size between 10-20 nm. The presence of Au in the shell was confirmed by EDX studies, with corroborating data from XPS measurements showing a significant contribution of both Au and Pd in the spectra, with the Au signal increasing as the total Au content of the catalyst increased. No PdO was observed, suggesting a complete reduction of the metal chloride nanoparticles. Unlike similar catalysts prepared by sol-immobilisation methodology, the core-shell structures showed excellent stability during the hydrogen peroxide synthesis reaction, and no catalyst deactivation was observed over 4 reuse cycles. This is the first time the preparation of stable core-shell particles have been reported using microwave assisted reduction. The observation that these particles are core-shell, without the need of a complicated synthesis or high thermal treatment and form in just 15 minutes presents an exciting opportunity for this experimental technique. A series of 1 wt% supported Au, Pd and AuPd nanoalloy catalysts were prepared via microwave assisted reduction of PdCl 2 and HAuCl 4 in a facile, one pot process.