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

纳米颗粒/团簇最重要的应用之一是多相催化，可以利用大的表面体积比。大多数情况下，这些团簇然后沉积在一些基底上，这使得对催化反应细节的详细理论和/或实验研究非常困难。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。该项目的目标是发展一个简单的模型反应的原子理解，即一氧化碳的氧化。作为催化剂，钛和钒氧化物团簇将被研究，它们依次沉积在石墨烯或二氧化硅上。研究N = x+y到50左右的不同M(x)O(y)簇。化学计量簇（M = Ti时y/x = 2, M = V时y/x = 2.5）和近化学计量簇（O富或O贫）都应进行研究。第一个挑战将是确定集群的结构。为此，我们将采用多年来用于分离气相纳米颗粒的无偏方法。作为一种方法，我们将对随后沉积在衬底上的气相颗粒完全使用这些方法。作为替代方案，我们将确定直接在衬底上创建此类簇的最佳结构。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，他的经验将对项目大有裨益。几年来，她一直从事催化的理论研究，这一经验对我们自己的经验有很好的补充。需要研究不同类型催化剂的催化反应：气相分离的团簇，沉积在衬底上的团簇，以及直接在衬底上生长的团簇。该项目预计将解决以下问题：金属氧化物簇的氧是否在催化反应中发挥积极作用，化学计量或近化学计量（贫氧或富氧）簇是更好的催化剂，催化反应的底物有多重要。

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.