Structure-Dependent Properties of Silver-Decorated 3D-Reduced Graphene Oxide Nanocomposites: Influence of Reagent Addition Sequence and Applications in Electrochemical Sensing

Abstract

This work aimed to demonstrate how careful control of the reagent concentration and the order of their addition can be used to fine-tune the characteristics of 3D-reduced graphene oxide structures decorated with silver and how this affects the applicability of these materials as electrochemical sensors. The materials were prepared by using an environmentally friendly single-step route in an autoclave, using only water as a solvent and ascorbic acid as a reductant, while varying the order of addition of the reagents and the amount of metal precursors. The presence of cetyltrimethylammonium bromide (CTAB) surfactant leads to the formation of Ag₂O particles in addition to pure Ag. A greater quantity of metal precursors resulted in a more compact macrostructure with smaller particles. The late addition of CTAB promoted the formation of smaller silver nanoparticles, which preferentially decorated the edges and folds of the rGO sheets. Computational calculations allowed for the elucidation of the mechanism responsible for this preferential morphology. The main advantage of the method used is its ability to synthesize simultaneously and in large quantities different materials in a fast, single-step approach. The synthesis route can influence the formation and characteristics of the silver particles, such as their composition, size, and shape. This architecture creates efficient conduction networks with maximum utilization of spaces and interfaces, acting as a conductive layer for the Ag or Ag/Ag₂O nanoparticles that decorate the macrostructure. The macrostructures showed applicability in furosemide sensing, with LD and LQ reaching 21 ± 2 and 69 ± 8 μmol L^–1, respectively.