A Systematic Study of the One-Pot Fabrication of Anisotropic Silver Nanoplates with Controllable Size and Shape for SERS Amplification

Abstract

This study reported comprehensive and systematic investigations on size and shape control of silver nanoplates (SNPs) through a simple synthesis route where individual effects of each reactant on surface plasmon resonance of silver nanoplates were thoroughly investigated. SNPs were successfully fabricated via chemical reduction of AgNO3 with the aid of TSC, PVP, NaBH4, and H2O2 as a primary capping agent, secondary capping agent, reducing agent, and oxidative etchant, respectively. The role and effects of each reagent on the size and uniformity of SNPs during the synthesis were deeply investigated. The results showed that both TSC and H2O2 played critical roles in the growth of SNPs. Sufficient amount of TSC in the solution ([TSC]:[Ag+] molar ratio ≤ 22.5) would favor the formation of small-sized SNPs, while large-sized SNPs could be obtained at an excessive concentration of TSC. In addition to TSC, H2O2 was also essential for the formation of SNPs whose size increased with the addition of H2O2. In contrast, PVP did not play a major role in the formation of SNPs. It functioned as a secondary capping agent to prevent the formation of larger SNPs and facilitated the production of small-sized SNPs with equal uniformity. This role of PVP was particularly significant at the low level of TSC. The results were crucial for deeply understanding the individual effects of each reagent on the size and uniformity of SNPs so as to control the size and shape of SNPs for better surface-enhanced Raman scattering (SERS) signals of 4-mercapto benzoic acid (4-MBA).