Medium-sized Au₄₀(SR)₂₄ and Au₅₂(SR)₃₂ nanoclusters with distinct gold-kernel structures and spectroscopic features

Authors

Wen Wu Xu, Chinese Academy of Sciences
Yadong Li, Chinese Academy of Sciences
Yi Gao, Shanghai Institute of Applied PhysicsFollow
Xiao Cheng Zeng, University of Nebraska-LincolnFollow

Date of this Version

2015

Citation

Nanoscale, 2016, 8, 1299–1304

DOI: 10.1039/c5nr07810e

Comments

Used by permission.

Abstract

We have analyzed the structures of two medium-sized thiolateprotected gold nanoparticles (RS-AuNPs) Au₄₀(SR)₂₄ and Au₅₂(SR)₃₂ and identified the distinct structural features in their Au kernels [Sci. Adv., 2015, 1, e1500425]. We find that both Au kernels of the Au₄₀(SR)₂₄ and Au₅₂(SR)₃₂ nanoclusters can be classified as interpenetrating cuboctahedra. Simulated X-ray diffraction patterns of the RS-AuNPs with the cuboctahedral kernel are collected and then compared with the X-ray diffraction patterns of the RS-AuNPs of two other prevailing Au-kernels identified from previous experiments, namely the Ino-decahedral kernel and icosahedral kernel. The distinct X-ray diffraction patterns of RS-AuNPs with the three different types of Au-kernels can be utilized as signature features for future studies of structures of RS-AuNPs. Moreover, the simulated UV/Vis absorption spectra and Kohn–Sham orbital energy-level diagrams are obtained for the Au₄₀(SR)₂₄ and Au₅₂(SR)₃₂, on the basis of time-dependent density functional theory computation. The extrapolated optical bandedges of Au₄₀(SR)₂₄ and Au₅₂(SR)₃₂ are 1.1 eV and 1.25 eV, respectively. The feature peaks in the UV/Vis absorption spectra of the two clusters can be attributed to the d → sp electronic transition. Lastly, the catalytic activities of the Au₄₀(SR)₂₄ and Au₅₂(SR)₃₂ are examined using CO oxidation as a probe. Both medium-sized thiolate-protected gold clusters can serve as effective stand-alone nanocatalysts.