In situ observation of CO oxidation on Ag110(2 x 1)-O by scanning tunneling microscopy: structural fluctuation and catalytic activity.
In situ observation of CO oxidation on Ag110(2 x 1)-O by scanning tunneling microscopy: structural fluctuation and catalytic activity.
复制标题
DOI：
10.1021/jp0512154
复制
发表时间：
2005-07
期刊：
影响因子：
--
通讯作者：
O. Nakagoe;Kazuya Watanabe;N. Takagi;Y. Matsumoto
中科院分区：
文献类型：
--
作者：
O. Nakagoe;Kazuya Watanabe;N. Takagi;Y. Matsumoto
在一维Ag-O-Ag-O-链周期性排列的Ag（110）（nx 1）-O表面上，利用变温扫描隧道显微镜（VT-STM）研究了CO对O吸附原子的清洗反应.基于在不同温度下的反应过程中的表面结构变化的STM原位观察，我们发现，反应动力学显着影响的AgO链的结构转变从一个固体直线配置的动态波动配置。在230 K以下，当链是直链时，反应仅在链的末端发生，因此反应以零级动力学进行，反应前沿沿着链传播。反应速率的温度依赖性产生41 kJ/mol的活化势垒和1.7 × 10（3）cm（-2）s（-1）的指前因子。在室温下，当几乎一半的O吸附原子被消除并且链开始波动时，反应速率急剧加速。在链涨落的作用下，相当于链末端的活性中心的动态形成导致了反应速率的非线性增加。
On the added-row reconstructed Ag(110)(nx1)-O surfaces where one-dimensional -Ag-O-Ag-O- chains arrange periodically, the clean-off reaction of O adatoms by CO was investigated using variable temperature scanning tunneling microscopy (VT-STM). Based on the in situ STM observations of the surface structure variation in the course of the reaction at various temperatures, we found that the reaction kinetics are significantly affected by the structural transition of AgO chains from a solid straight line configuration to dynamically fluctuating configurations. Below 230 K where the chains are straight, the reaction takes place only at the end of the chains, so that the reaction progresses in the zero-order kinetics with the reaction front propagating along the chain. The temperature dependence of the reaction rates yields the activation barrier of 41 kJ/mol and the preexponential factor of 1.7 x 10(3) cm(-2) s(-1). At room temperature, the reaction rate is drastically accelerated when almost half of the O adatoms are eliminated and the chains start fluctuating. The dynamic formation of active sites equivalent to the end of chains upon the chain fluctuation results in the nonlinear increase of the reaction rate.