Highly accessible aqueous synthesis of well-dispersed dendrimer type platinum nanoparticles and their catalytic applications

The application of novel methodologies to the synthesis of nanomaterials is still a challenge in many different technological and scientific fields. New efficient and reproducible synthetic methodologies, that produce fewer residues and reduce the cost of raw materials must be developed. In the present work, we have explored the attractive possibility to apply the cheap iron (Ⅱ) sulphate salt in the reduction process of the K₂PtCl₄ to produce colloids suspensions. The synthesis took places in water and was assisted by sodium citrate (SC) using polyvinylpyrrolidone (PVP) as a surfactant. The adjustment of this novelty process allows obtaining well-dispersed and sub-20 nm dendrimer-type platinum nanoparticles (Pt D-NPs). The nano-dendrimers produced have been characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), XRD spectroscopy, inductive couple plasma (ICP) analysis, Fourier transform infrared (FT-IR) and ultraviolet–visible (UV–vis) spectroscopy. Interesting conformational results derived from the size and shape will be discussed. Catalytic application of the Pt D-NPs has been explored in the reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP) in aqueous media at room temperature obtained TOF value of 253 min^-1. Finally, our Pt D-NPs were tested as artificial metalloenzyme showing catechol oxidase activity for oxidation of L-DOPA.