Preparation of supported mono- and bimetallic nanoparticles by Supercritical Fluid Reactive Deposition (SFRD)

与传统催化剂相比，纳米粒子和纳米合金具有独特的性质和更强的催化活性，在催化应用中受到越来越多的关注。到目前为止，单金属和双金属纳米颗粒的制备通常采用传统的湿法浸渍技术，但存在一些缺点，如所获得的产品性质控制不佳。相反，SFRD技术为制备单金属和双金属纳米颗粒提供了一种替代的和有前途的方法，因为它提供了控制颗粒尺寸和分布、均匀性和浓度的方法。单组分SFRD过程包括三个步骤，即：前体在scCO2中的溶解，前体在载体上的吸附或吸附，以及吸附的前体转化为其金属形式。为了利用SFRD合成双金属纳米颗粒，自然而然地出现了两种方法，即同时沉积和顺序沉积。因此，在拟议的项目中，将在不同的载体上沉积各种单金属和双金属纳米颗粒。与单组分SFRD类似，在同时SFRD中，前驱体(S)在SCCO_2存在下在载体上的吸附是至关重要的，将用实验和理论方法进行研究。因此，本项目的目标是通过SFRD制备负载型单金属和双金属纳米颗粒，并研究前驱体和衬底性质、吸附行为和还原方法对金属负载量、颗粒大小和分布的影响。

Due to unique properties and enhanced catalytic activities compared to conventional catalysts, nanoparticles and nanoalloys have been attracting increasing attention in catalytic applications. So far, mono- and bi-metallic nanoparticles were usually prepared by using conventional wet impregnation techniques that are associated with a few drawbacks such as poor control of the obtained product properties. In opposite thereto, the SFRD technique enables an alternative and promising method for the preparation of mono- and bimetallic nanoparticles, since it provides to control the particle size and distribution, homogeneity and concentration. The single component SFRD process consists of three steps that are: the dissolution of a precursor in scCO2, adsorption or sorption of the precursor onto support and the conversion of the adsorbed precursor to its metal form. Two approaches naturally arise in order to synthesize bimetallic nanoparticles using SFRD, which are simultaneous and sequential deposition. Therefore, within the proposed project, various mono- and bimetallic nanoparticles will be deposited on different supports. Similar to single component SFRD, in simultaneous SFRD the adsorption of precursor(s) on the support in the presence of scCO2 is of crucial importance and will be investigated applying experimental and theoretical approaches. Thus, the objectives of this proposed project are to prepare supported mono- and bimetallic nanoparticles via SFRD and to investigate the influence of precursor and substrate properties, adsorption behavior and reduction method on metal loading, particle size and distribution.