A mild colloidal strategy for controlling the morphology of reduced graphene oxide–Ag nanowire hybrids

Abstract

A novel hybrid nanocomposite has been synthesized via a polyol-based proceed, consisting of polyvinylpyrrolidone (PVP) coated silver nanowires (Ag NWs) decorating Reduced Graphene Oxide (RGO) sheets, functionalized with histidine (His). While conventional methods involve mixing pre-synthesized Ag NWs with graphene derivatives, an approach that typically results in a weak electron coupling between the components, this study presents an in situ synthesis strategy designed to promote a stronger interfacial interaction and, hence, electronic connectivity within the nanocomposite. In this nanocomposite, the Ag NWs are coordinated by His molecules, which are non covalently anchored to the RGO basal plane through aromatic π–π stacking interactions. His has been purposefully selected due to its multifunctional role: it facilitates the liquid-phase exfoliation of RGO in water, enables stable dispersion in ethylene glycol, which is an environmentally friendly solvent serving as the reducing agent in the polyol reaction, and acts as a molecular linker between the Ag NWs and the RGO surface. The influence of various experimental parameters on the morphology and size distribution of the Ag NWs across the His-RGO scaffold has been thoroughly explored through spectroscopy and microscopy techniques, enabling a deeper understanding of the nanocomposite's formation mechanism. The findings have revealed that the Ag NWs grow in situ on the His-RGO sheets, originating from pre-synthesized AgCl nanocubes that anchor selectively at the coordinating sites of His. Notably, well dispersed His-RGO flakes decorated with morphologically controlled Ag NWs have been successfully obtained in ethanol suspension. These nanostructures can hold significant promise as functional materials for diverse applications, including electrochemical and Surface-Enhanced Raman Spectroscopy (SERS) sensors, temperature sensors, antimicrobial coatings, and thermal management technologies.