Interfacial Growth of Large Area Single-Crystalline Silver Sheets Through Ambient Microdroplets

Depanjan Sarkar; Anirban Som; Keerthana Unni; Sujan Manna; Pradeep Thalappil

doi:10.1002/smll.202400159

Interfacial Growth of Large Area Single-Crystalline Silver Sheets Through Ambient Microdroplets

Small. 2024 Apr 26:e2400159. doi: 10.1002/smll.202400159. Online ahead of print.

Authors

Depanjan Sarkar^{1

2}, Anirban Som^{1

2}, Keerthana Unni^{1

2}, Sujan Manna^{1

2}, Pradeep Thalappil^{1

2}

Affiliations

¹ DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai, 60036, India.
² Centre of Excellence on Molecular Materials and Functions, Department of Chemistry, Indian Institute of Technology Madras, Chennai, 60036, India.

PMID: 38671561
DOI: 10.1002/smll.202400159

Abstract

The creation of micrometer-sized sheets of silver at the air-water interface by direct deposition of electrospray-generated silver ions (Ag⁺) on an aqueous dispersion of reduced graphene oxide (RGO), in ambient conditions, is reported. In the process of electrospray deposition (ESD), an electrohydrodynamic flow is created in the aqueous dispersion, and the graphene sheets assemble, forming a thin film at the air-water interface. The deposited Ag⁺ coalesce to make single-crystalline Ag sheets on top of this assembled graphene layer. Fast neutralization of Ag⁺ forming atomic Ag, combined with their enhanced mobility on graphene surfaces, presumably facilitates the growth of larger Ag clusters. Moreover, restrictions imposed by the interface drive the crystal growth in 2D. By controlling the precursor salt concentration, RGO concentration, deposition time, and ion current, the dimensionality of the Ag sheets can be tuned. These Ag sheets are effective substrates for surface-enhanced Raman spectroscopy (SERS), as demonstrated by the successful detection of methylene blue at nanomolar concentrations.

Keywords: SERS; ambient ions; electrospray deposition; graphene; microdroplets; silver sheets.