Plasmonic twinned silver nanoparticles with molecular precision.

Huayan Yang,Huaqi Huang,Lin Gu,Yu Wang,Nanfeng Zheng,Xi Chen,Gang Li,Junchao Wu,Hannu Häkkinen,Xiaojing Zhao,Zichao Tang,Dongdong Wang,Birger Dittrich,Lauri Lehtovaara,Alison J Edwards,Chaofa Xu,Juanzhu Yan

doi:10.1038/ncomms12809

Abstract

Determining the structures of nanoparticles at atomic resolution is vital to understand their structure–property correlations. Large metal nanoparticles with core diameter beyond 2 nm have, to date, eluded characterization by single-crystal X-ray analysis. Here we report the chemical syntheses and structures of two giant thiolated Ag nanoparticles containing 136 and 374 Ag atoms (that is, up to 3 nm core diameter). As the largest thiolated metal nanoparticles crystallographically determined so far, these Ag nanoparticles enter the truly metallic regime with the emergence of surface plasmon resonance. As miniatures of fivefold twinned nanostructures, these structures demonstrate a subtle distortion within fivefold twinned nanostructures of face-centred cubic metals. The Ag nanoparticles reported in this work serve as excellent models to understand the detailed structure distortion within twinned metal nanostructures and also how silver nanoparticles can span from the molecular to the metallic regime.

Highlights

Determining the structures of nanoparticles at atomic resolution is vital to understand their structure–property correlations
The transmission electron microscopy (TEM) images revealed that these thiolated Ag nanoparticles had a tight particle-size distribution at B2 nm
Their sizes lie in the region where metallic Ag nanoparticles are said to develop SPR34 and provide scope to assess the occurrence of surface plasmon resonance (SPR) from the viewpoint of associated quantum mechanical calculations

Summary

Introduction

Determining the structures of nanoparticles at atomic resolution is vital to understand their structure–property correlations. Density functional theory (DFT) studies reveal that the smaller nanoparticle has molecular character with a small but distinct energy gap (band gap) between occupied and unoccupied orbitals (highest occupied molecular orbital–lowest unoccupied molecular orbital gap), whereas the larger one is fully metallic without a band gap This leads to emergence of the surface plasmon incorporating contributions from the organic ligand layer. These two structurally determined systems represent important exemplars of the cross-over of Ag nanoparticles from the molecular to the metallic regime

Methods

Results

Conclusion