UV‐Induced Synthesis and Stabilization of Surfactant‐Free Colloidal Pt Nanoparticles with Controlled Particle Size in Ethylene Glycol

Abstract

The conventional temperature‐induced polyol synthesis of platinum nanoparticles is a powerful and well‐established method for the preparation of stable, surfactant‐free platinum nanoparticles (Pt NPs) with controlled shape, size and size distribution. Recently, we reported that exposure to daylight leads to the formation of Pt NPs from precursor solutions, suggesting that a parallel approach of UV‐induced polyol synthesis could be a cheaper and more widely applicable alternative. Here we report a controlled size and size distribution for Pt NPs prepared using UV irradiation instead of thermal treatment. Results demonstrate that, depending on the concentration of NaOH in the reaction mixture, the size of produced nanoparticles can vary between 1 and 5.8 nm. We also show, for the first time, how NaOH affects the formation of organic side products, which alters Pt NPs stability, and demonstrate a method for the preparation of stable nanoparticle suspensions with an average particle size of 5.8 nm.

Controlled Synthesis of Surfactant‐Free Water‐Dispersible Colloidal Platinum Nanoparticles by the Co4Cat Process

“…The same ageing effect was achieved by irradiating the Pt IV salt solutions at 20 m m H 2 PtCl 6 for 30 min with UV lamps (Figure S3 in the Supporting Information). This color change relates to the disappearance of a peak at 268 nm in the UV absorption spectra of the solutions, indicative of the consumption of the initial Pt IV −Cl complex . Interestingly, this peak did not significantly change over time if the solution was kept in the dark.…”

“…This color change relatest o the disappearance of ap eak at 268 nm in the UV absorption spectra of the solutions, indicative of the consumption of the initial Pt IV ÀCl complex. [39] Interestingly,t his peak did not significantly change over time if the solution was kept in the dark. This means that the ageingp rocess led to as olution with a majority of Pt II species withoutt he formation of Pt 0 NPs (Table 3a nd Figure S4 in the Supporting Information).…”

“…The synthesis of unprotected Pt NPs in alkaline EG has been thermally induced in oilbath synthesis, [12] microwave synthesis, [40] at ambient temperature and light, [41] or under UV light. [39] This panel of suitable strategies makest he synthesis highly tunable for specific needs. The same synthetic approaches are suitablew ith alkaline mono-alcohols as solvents.…”

Perspective of Surfactant‐Free Colloidal Nanoparticles in Heterogeneous Catalysis

“…Yet, while the surfactant functionalization represents a great chance for the development of novel and highly selective catalytic nanomaterials, a mandatory prerequisite to avoid impurity‐induced crossover interactions is constituted by the availability of high purity surfactant‐free NPs prior to surfactant functionalization or the inclusion of the ligands within the synthesis process. To that end, in wet chemical synthesis, surfactant‐free NPs may be obtained by the ethylene glycol method for example used by the Bäumer group, the Somorjai group or the Arenz group . However, regarding the scale of typical nanoparticle concentrations (mg/L), various impurities being present in superior number even in pro analysi quality chemicals needs to be considered.…”

A Facile One-Pot Synthesis of Versatile PEGylated Platinum Nanoflowers and Their Application in Radiation Therapy

“…So, it is essential to prepare small size, biocompatible, nontoxic NPs. The synthesis of Pt NPs has already been studied using different methods such as chemical reduction [20], light assisted reduction by γ-rays radiation [21], UV radiation [22], and biologically assisted procedures [23]. Among these techniques, radiolysis is considered as an effective method for the synthesis of metallic NPs [24].…”