Pt–Au Alloying at the Nanoscale

• Published in: Nano letters Vol. 12; no. 8; pp. 4289 - 4299
• Main Authors: Petkov, Valeri, Wanjala, Bridgid N, Loukrakpam, Rameshwori, Luo, Jin, Yang, Lefu, Zhong, Chuan-Jian, Shastri, Sarvjit
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 08.08.2012
• Subjects: Alloying effects; Alloys; Anodizing; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Formations; Gold; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Materials science; Methods of nanofabrication; Methyl alcohol; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Physics; Platinum; Platinum base alloys; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); High-energy resonant XRD; atomic pair distribution functions; catalysis; reverse Monte Carlo modeling; structure of metallic nanoparticles; Calcium selenides; Gold alloys; Platinum alloys; Distortion; Computerized simulation; XRD; Nanostructures; Bond lengths; Nanoparticles; Nanometer scale; High energy; Alloying; Catalyst activity; Pair distribution function; Nanostructured materials; Nanomaterial synthesis; Methanol
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl302329n

The formation of nanosized alloys between a pair of elements, which are largely immiscible in bulk, is examined in the archetypical case of Pt and Au. Element specific resonant high-energy X-ray diffraction experiments coupled to atomic pair distribution functions analysis and computer simulations prove the formation of Pt–Au alloys in particles less than 10 nm in size. In the alloys, Au–Au and Pt–Pt bond lengths differing in 0.1 Å are present leading to extra structural distortions as compared to pure Pt and Au particles. The alloys are found to be stable over a wide range of Pt–Au compositions and temperatures contrary to what current theory predicts. The alloy-type structure of Pt–Au nanoparticles comes along with a high catalytic activity for electrooxidation of methanol making an excellent example of the synergistic effect of alloying at the nanoscale on functional properties.