Size dependent electronic, structural and catalytic properties of nanostructured supported metal oxide clusters

纳米粒子/簇合物最重要的应用之一是多相催化，可以利用大的比表面体积比。大多数情况下，团簇被沉积在一些底物上，这使得对催化反应的细节进行详细的理论和/或实验研究变得非常困难。催化反应中最重要的一类是某些体系的氧化反应。对于这些反应，使用金属氧化物作为催化剂可能是有利的。拟议项目的目标是发展对一个简单的模型反应--CO的氧化--的原子理解。作为催化剂，将研究钛和钒氧化物团簇，然后将其沉积在石墨烯或二氧化硅上。应研究N=xy至50左右的不同M(X)O(Y)团簇。既要研究化学计量比团簇(对于M=Ti，y/x=2，对于M=V，y/x=2.5)，也要研究接近化学计量比的富氧或贫氧。第一个挑战将是确定集群的结构。为此，我们将应用几年来对气相中分离的纳米颗粒所使用的无偏方法。作为一种方法，我们将对气相中的颗粒使用这些方法，这些颗粒随后将被沉积在衬底上。作为另一种选择，我们将确定当直接在衬底上生成此类团簇时的最佳结构。随后，我们将研究CO的氧化。这一部分将与印度同事Neetu Goel博士密切合作完成，他的经验将对该项目大有裨益。几年来，她一直致力于催化的理论研究，这是对我们自己经验的极好补充。催化反应应针对不同类型的催化剂进行研究：气相中的孤立团簇、沉积在底物上的团簇和直接生长在底物上的团簇。该项目预计将解决以下问题：金属氧化物团簇中的氧在催化反应中是否起到积极作用，化学计量比或接近化学计量比(贫氧或富氧)的团簇是更好的催化剂，基质对催化反应有多重要。

One of the most important applications of nanoparticles / clusters is that of heterogeneous catalysis, for which the large surface-to-volume ration can be exploited. Most often, the clusters are then deposited on some substrate, which makes detailed theoretical and/or experimental studies of the details of the catalytic reactions very difficult. One of the most important classes of catalytic reactions is the oxidation of some system. For those reactions, it can be of advantage to use metal oxides as catalysts.The goal of the proposed project is to develop an atomistic understanding of a simple model reaction, the oxidation of CO. As catalysts, titanium and vanadium oxide clusters will be studied that in turn are deposited on either graphene or silica. Different M(x)O(y) clusters with N = x+y up to around 50 shall be studied. Both stoichiometric clusters (y/x = 2 for M = Ti, y/x = 2.5 for M = V) as well as near-stoichiometric either O rich or O poor shall be studied. The first challenge will be to determine the structures of the clusters. To this end, we shall apply the unbiased methods that we have been used for isolated nanoparticles in the gas phase since several years. As one approach we shall use exactly those methods for the particles in the gas phase that subsequently shall be deposited on the substrate. As an alternative we shall determine the optimal structures for such clusters when created directly on the substrate.Subsequently, we shall study the oxidation of CO. This part shall be done in close collaboration with an Indian colleague, Dr. Neetu Goel, whose experience will be of great benefit to the project. Since several years she has been working on theoretical studies of the catalysis, an experience that in excellent way complements our own. The catalytic reaction shall be studied for different types of catalysts: isolated clusters in the gas phase, such clusters deposited on the substrate, and clusters grown directly on the substrate.The project is expected to address the following issues: does oxygen of the metal oxide clusters play an active role in the catalytic reaction, are stoichiometric or near-stoichiometric (oxygen-poor or -rich) clusters the better catalysts, how important are the substrates for the catalytic reaction.