Stark Kirsty, Cheng Cheng, Hitchcock James P, White Alison L, Hondow Nicole, Biggs Simon, Cayre Olivier J
School of Chemical and Process Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom.
School of Chemical Engineering, University of Queensland, St. Lucia, Queensland 4072, Australia.
J Colloid Interface Sci. 2022 Dec 15;628(Pt B):840-850. doi: 10.1016/j.jcis.2022.08.015. Epub 2022 Aug 5.
Emulsion droplets offer an alternative to solid supports as templates for the deposition of metallic nanoparticles. An emulsion interface provides the opportunity to exploit both sides of the nanoparticles and to utilise the liquid core as a microreactor in addition to forming a scaffold for encapsulation. However, despite the extensive literature studying a very broad range of factors influencing the characteristics of particle-stabilised (Pickering) emulsions, most reports focus on particles of diameters >100 nm and a very small proportions consider particles of diameters <10 nm. For catalytic purposes of course, the latter species are of utmost interest. Here, we report the synthesis of poly(vinyl pyrrolidone) (PVP) stabilised platinum nanoparticles, where the platinum core ranges between 3 and 5 nm in diameter and their subsequent use as emulsifiers for the oil-water interface where they form a densely packed layer. The nanoparticle density at the interface is quantified by both measuring the remaining concentration of nanoparticles in the aqueous phase after adsorption and also directly at the oil-water interface via cryo-TEM. The effect of electrolyte concentration and of addition of excess PVP in the bulk aqueous nanoparticle dispersion prior to emulsification on the resulting nanoparticle density at the oil-water interface is also determined.
乳液滴作为金属纳米颗粒沉积的模板，为固体载体提供了一种替代方案。乳液界面不仅为纳米颗粒的两面提供了利用机会，还能将液芯用作微反应器，此外还能形成用于封装的支架。然而，尽管有大量文献研究了影响颗粒稳定（皮克林）乳液特性的广泛因素，但大多数报告关注的是直径大于100nm的颗粒，只有极少数报告考虑直径小于10nm的颗粒。当然，就催化目的而言，后一种颗粒最受关注。在此，我们报告了聚（乙烯基吡咯烷酮）（PVP）稳定的铂纳米颗粒的合成，其中铂核直径在3至5nm之间，以及它们随后用作油水界面乳化剂的情况，在该界面它们形成了紧密堆积的层。通过测量吸附后水相中纳米颗粒的剩余浓度以及通过低温透射电子显微镜直接在油水界面处对界面处纳米颗粒的密度进行了量化。还确定了乳化前本体水相纳米颗粒分散体中电解质浓度和过量PVP添加对油水界面处所得纳米颗粒密度的影响。
