Neuwirth D, Eckhard J F, Visser B R, Tschurl M, Heiz U
Lehrstuhl für Physikalische Chemie, Chemistry Department & Catalysis Research Center, Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany.
Phys Chem Chem Phys. 2016 Mar 21;18(11):8115-9. doi: 10.1039/c5cp07245j.
The reaction of cationic tantalum clusters (Tan(+), n = 13-40) with molecular oxygen is studied under multi-collision conditions and at different temperatures. Consecutive reaction proceeds in several steps upon subsequent attachment of O2. All cluster sizes exhibit fast reaction with oxygen and form a characteristic final reaction product. The time-dependent product analysis enables the fitting to a kinetic model with the extraction of all the rate constants. Determined rate constants reveal the existence of two different regimes, which are interpreted as a change in the reaction mechanism. Based on the temperature-dependent reaction behavior, it is proposed that the reaction changes from a dissociative to a molecular adsorption of oxygen on the clusters. It is found that both regimes appear for all cluster sizes, but the transition takes place at different intermediate oxides TanOx(+). In general it is observed that transition occurs later for larger clusters, which is attributed to an increased cluster surface.
在多碰撞条件和不同温度下，研究了阳离子钽簇（Tan(+)，n = 13 - 40）与分子氧的反应。在随后附着O2时，连续反应分几步进行。所有簇尺寸的物质都与氧发生快速反应，并形成特征性的最终反应产物。随时间变化的产物分析能够拟合动力学模型并提取所有速率常数。确定的速率常数揭示了两种不同的反应机制，这被解释为反应机理的变化。基于温度依赖的反应行为，提出反应从氧在簇上的解离吸附转变为分子吸附。发现所有簇尺寸的物质都出现这两种反应机制，但转变发生在不同的中间氧化物TanOx(+)处。一般观察到，较大的簇转变发生得较晚，这归因于簇表面的增加。
