Lei, YuZhao, HaiyanRivas, Rosa DiazLee, SungsikLiu, BinLu, JunlingStach, EricWinans, Randall E.Chapman, Karena W.Greeley, Jeffrey P.Miller, Jeffrey T.Chupas, Peter J.Elam, Jeffrey W.2014-11-062014-11-062014-06-12http://hdl.handle.net/2097/18642We investigated changes in the Pt–Pt bond distance, particle size, crystallinity, and coordination of Pt nanoparticles as a function of particle size (1–3 nm) and adsorbate (H2, CO) using synchrotron radiation pair distribution function (PDF) and X-ray absorption spectroscopy (XAS) measurements. The ∼1 nm Pt nanoparticles showed a Pt–Pt bond distance contraction of ∼1.4%. The adsorption of H2 and CO at room temperature relaxed the Pt–Pt bond distance contraction to a value close to that of bulk fcc Pt. The adsorption of H2 improved the crystallinity of the small Pt nanoparticles. However, CO adsorption generated a more disordered fcc structure for the 1–3 nm Pt nanoparticles compared to the H2 adsorption Pt nanoparticles. In situ XANES measurements revealed that this disorder results from the electron back-donation of the Pt nanoparticles to CO, leading to a higher degree of rehybridization of the metal orbitals in the Pt-adsorbate system.en-USThis Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).Platinum nanoparticlesHeterogeneous catalystX‐ray absorption spectroscopyPair distribution functionBond distanceContractionLigandsArticle (author version)