IMST Institute for Materials and Surface Technology, University of Applied Sciences Kiel, Kiel, Schleswig-Holstein, Germany.
IMST Institute for Materials and Surface Technology, University of Applied Sciences Kiel, Kiel, Schleswig-Holstein, Germany.
Ultrason Sonochem. 2019 Mar;51:138-144. doi: 10.1016/j.ultsonch.2018.10.034. Epub 2018 Oct 26.
The sonochemical processing of nanomaterials in a solution is well established and has been advantageously used for a variety of nanomaterials and morphologies thereof. In general, high energy and high frequency ultrasound is applied to a solution containing the ionic species of the elements to be reduced as well as a certain amount of reducing chemicals. For further applications such as catalysis washing, filtering, dispersion and mounting on or mixing in a substrate are necessary. A sonochemical processing of nanomaterials directly on a substrate could make all these steps obsolete. Herein we show that noble metal and nanoalloy nanoparticles (NPs) can directly be processed on nanocarbon and titanium nitride surfaces using a simple ultrasound laboratory cleaner in aqueous solutions that are free from any reducing chemicals. The process is demonstrated on Au-NPs and nanoalloys of AuPd and PdPt which form a dense distribution on the substrate surface. To illustrate the catalytic activity of the NPs, the electrocatalytic performance of one AuPd-nanoalloy is demonstrated. The results are discussed in terms of reduction phenomena occurring at the interface between the ultrasonic cavitation and the substrate. We think that these reduction phenomena are mediated by the formation of reducing radicals at the substrate surface that are in turn driven by OH radicals from water sonolysis. Electrochemical current measurement at 0 V seem to support the existence of reducing currents during measurements under chopped ultrasound in an aqueous solution of HAuCl in comparison to measurements in water.
在溶液中通过超声化学处理纳米材料已经得到了很好的确立，并已被有利地用于多种纳米材料及其形态。一般来说，高能高频超声被应用于含有待还原元素的离子物种以及一定量的还原化学物质的溶液中。对于进一步的应用，如催化洗涤、过滤、分散以及在衬底上的安装或混合，都是必要的。在衬底上直接进行纳米材料的超声化学处理可以使所有这些步骤变得多余。在此，我们表明，使用简单的超声实验室清洁器，在不含任何还原化学物质的水溶液中，可以直接在纳米碳和氮化钛表面上处理贵金属和纳米合金纳米颗粒（NPs）。该过程在 Au-NPs 和 AuPd 和 PdPt 的纳米合金上得到了证明，它们在衬底表面上形成了密集的分布。为了说明 NPs 的催化活性，我们展示了一种 AuPd 纳米合金的电催化性能。根据超声空化与衬底之间界面处发生的还原现象来讨论结果。我们认为，这些还原现象是由在衬底表面形成的还原自由基介导的，而这些自由基反过来又被水超声分解产生的 OH 自由基所驱动。与在水中的测量相比，在含有 HAuCl 的水溶液中进行超声脉冲测量时，电化学电流测量在 0 V 似乎支持在测量过程中存在还原电流。
