Evidence of Pd segregation and stabilization at edges of AuPd nano-clusters in the presence of CO: A combined DFT and DRIFTS study

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• 作者：Beien Zhu ; Gode Thrimurthulu ; Laurent Delannoy ; Catherine Louis ; Christine Mottet ; J茅r么me Creuze ; Bernard Legr ; Hazar Guesmi
• 关键词：CO adsorption ; AuPd ; DFT ; Catalysis ; DRIFTS ; Nanoalloy
• 刊名：Journal of Catalysis
• 出版年：December, 2013
• 年：2013
• 卷：308
• 期：Complete
• 页码：272-281
• 全文大小：1889 K

文摘

Combined Density Functional Theory (DFT) calculations and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) were performed to study the distribution of Pd atoms in bimetallic AuPd nanoparticles in the presence of adsorbed CO. Compared to vacuum condition, the results showed evidence of Pd surface enrichment where both Pd monomers and Pd dimers could exist. The energetic stability calculated for several alloy configurations evidenced the preference of Pd to occupy under-coordinated edge sites in the presence of CO gas. Moreover, the calculation of the vibrational frequencies of adsorbed CO for the first time allowed the fine assignment of the complex experimental DRIFTS bands of CO interacting with the bimetallic nanoparticles and their evolution with time exposure. Electronic structure analysis shows preponderant 蟺-back-donation from under-coordinated Pd to CO inducing strong bonding on edge sites.