Adsorption of small molecules on helical gold nanorods: A relativistic density functional study. Issue 27 (11th August 2014)

• Record Type: Journal Article
• Authors: Liu, Xiao‐Jing; Hamilton, Ian
• Is Part Of: Journal of computational chemistry. Volume 35:Issue 27(2014)
• Page Start: 1967
• Page End: 1976
• Publication Date: 2014-08-11
• Subjects: Chemistry -- Data processing -- Periodicals; 542.85
• DOI: 10.1002/jcc.23711
• Languages: English
• ISSNs: 0192-8651

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>We study the adsorption of a variety of small molecules on helical gold nanorods using relativistic density functional theory. We focus on Au<sub>40</sub> which consists of a central linear strand of five gold atoms with seven helical strands of five gold atoms on a coaxial tube. All molecules preferentially adsorb at a single low‐coordinated gold atom on the coaxial tube at an end of Au<sub>40</sub>. In most cases, there is significant charge transfer (CT) between Au<sub>40</sub> and the adsorbate, for CO and NO<sub>2</sub>, there is CT from the Au<sub>40</sub> to adsorbate while for all other molecules there is CT from the adsorbate to Au<sub>40</sub>. Thus, Au<sub>40</sub>‐adsorbate can be described as a donor–accepter complex and we use charge decomposition analysis to better understand the adsorption process. We determine the adsorption energy order to be C<sub>5</sub>H<sub>5</sub>N >NO<sub>2</sub> > CO > NH<sub>3</sub> > CH<sub>2</sub>CH<sub>2</sub> > CH<sub>2</sub>CHCHO > NO > HCCH > H<sub>2</sub>S > SO<sub>2</sub> > HCN > CH<sub>3</sub>OH > H<sub>2</sub>CO > O<sub>2</sub> > H<sub>2</sub>O > CH<sub>4</sub> > N<sub>2</sub>. We find that the AuC, AuN, AuS, and AuO bonds are surprisingly strong, with clear implications for reactivity enhancement of the adsorbate. The AuH bond is relatively weak but, for interactions via an H atom that is bonded to a carbon atom (e.g., CH<sub>4</sub>), we find that there is large charge polarization of the AuHC moiety and partial activation of the inert CH bond. Although the AuS and AuO bonds are generally weaker than the AuC and AuN bonds, we find that adsorption of H<sub>2</sub>S or H<sub>2</sub>O causes greater distortion of Au<sub>40</sub> in the binding region. However, the degree of distortion is small and the helical structure is retained, demonstrating the stability of the helical Au<sub>40</sub> nanorod under perturbations. © 2014 Wiley Periodicals, Inc.</p> </abstract>