Tuning the surface plasmon resonance in gold nanocrystals with single layer carbon nitride

O Stroyuk,A Raevskaya,G Grodzyuk,S Schulze,V Yefanov,D R T Zahn,N Andriushina,M Skoryk

doi:10.1039/c8ra09454c

Abstract

The introduction of colloidal single-layer carbon nitride (SLCN) nanosheets at the stage of the formation of Au nanocrystals (NCs) in aqueous solutions allows the surface plasmon resonance peak position of gold/SLCN composites to be tuned in a relatively broad range of 520–610 nm. The effect is believed to originate from a strong electronic interaction between Au NCs and SLCN nanosheets attached to their surface as capping ligands and resulting in a decrease of the effective electron density on the Au NC surface. The SLCN nanosheets suppress direct interparticle interactions between Au NCs prohibiting additional plasmonic features typical for the Au NC associates. Species similar to SLCN in terms of functionalities but having no conjugated aromatic system, such as polyethyleneimine, only induce aggregation of Au NCs but do not allow the main surface plasmon resonance of the NCs to be tuned demonstrating the crucial role of electronic interaction between the NC surface and the aromatic SLCN sheets for the surface plasmon resonance tuning.

Highlights

The effect is believed to originate from a strong electronic interaction between Au NCs and single-layer carbon nitride (SLCN) nanosheets attached to their surface as capping ligands and resulting in a decrease of the effective electron density on the Au NC surface
The colloidal Au NCs loose stability at decreasing pH indicating that the NCs are stabilized most probably by adsorbed hydroxide anions as well as residual ascorbate anions and oxalate anions forming as a product of the oxidation of ascorbic acid
Colloidal Au NCs show a typical absorption spectrum (Fig. 2a, curve 1) composed of a continuous d–d transition band superimposed with a characteristic surface plasmon resonance (SPR) band peaked at 520 nm

Summary

Introduction

Gold nanocrystals (NCs) belong to the most intriguing and broadly studied objects of current research focused on nanodimensional materials.[1,2,3,4,5] The vivid effect of surface plasmon resonance (SPR) in the visible spectra range typical for Au NCs de nes the immense interest in their applications in various optical, opto-electronic, and sensing systems, the latter including surface-enhanced Raman spectroscopic sensing,[6,7] optical and electrochemical sensing,[1,5,8,9] medicine,[3,4,5] and catalysis.[2].

Results

Conclusion