Intermatrix synthesis of Ag, AgAu and Au nanoparticles by the galvanic replacement strategy for bactericidal and electrocatalytically active nanocomposites

The intermatrix synthesis (IMS) technique has proven to be an environmentally friendly methodology for the preparation of functional metal nanoparticles (FMNPs) on different reactive matrices. The distribution of these FMNPs is an important feature to control depending on the final application of the nanocomposite: bactericide assays for water treatment, heterogeneous catalysis, electrocatalytic effects and others. IMS offers the feasibility to control the FMNP distribution, taking into account the adequacy of the ion exchange form of the reactive matrix and the chemical nature of the reducing agent used for the synthesis (the Donnan effect). Consequently, AgAu–FMNPs and Au–FMNPs containing nanocomposites have been prepared by coupling a galvanic replacement stage to IMS, with tested bactericide features attributed to the distribution of the nanoparticles on the material. In addition, Ag–FMNPs and Au–FMNPs contained on multiwalled carbon nanotubes have been synthesized and used as conducting nanofillers for the development of amperometric nanocomposite sensors based on epoxy resin. The incorporation of these FMNPs into the nanocomposite sensor has shown significant electrocatalytic effects, obtaining enhanced electrochemical and analytical parameters, such as higher signal-to-noise ratios as well as better detection limits, quantification limits and sensitivities for the oxidation of ascorbic acid in water, which was used as a model analyte.