Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK.
Phys Chem Chem Phys. 2011 Feb 21;13(7):2528-38. doi: 10.1039/c0cp01852j. Epub 2010 Dec 10.
The oxidation of CO by Au/Fe(2)O(3) and Au/ZnO catalysts is compared in the very early stages of the reaction using a temporal analysis of products (TAP) reactor. For Au/Fe(2)O(3) pre-dosing the catalyst with (18)O labelled water gives an unexpected evolution order for the labelled CO(2) product with the C(18)O(2) emerging first, whereas no temporal differentiation is found for Au/ZnO. High pressure XPS experiments are then used to show that CO bond cleavage does occur for model catalysts consisting of Au particles deposited on iron oxide films but not when deposited on ZnO films. DFT calculations, show that this observation requires carbon monoxide to dissociate in such a way that cleavage of the CO bond occurs along with dynamically co-adsorbed oxygen so that the overall process of Au oxidation and CO dissociation is energetically favourable. Our results show that for Au/Fe(2)O(3) there is a pathway for CO oxidation that involves atomic C and O surface species which operates along side the bicarbonate mechanism that is widely discussed in the literature. However, this minor pathway is absent for Au/ZnO.
使用时间分辨产物分析（TAP）反应器比较了 Au/Fe(2)O(3) 和 Au/ZnO 催化剂在反应的早期阶段对 CO 的氧化作用。对于 Au/Fe(2)O(3)，用（18）O 标记的水对催化剂进行预剂量处理会导致标记的 CO(2)产物出现出人意料的演化顺序，其中 C(18)O(2)首先出现，而 Au/ZnO 则没有时间差异。然后使用高压 XPS 实验表明，对于由沉积在氧化铁薄膜上的金颗粒组成的模型催化剂，确实会发生 CO 键的断裂，但当沉积在 ZnO 薄膜上时则不会。DFT 计算表明，这种观察结果要求一氧化碳以这样的方式解离，即 CO 键的断裂与动态共吸附的氧一起发生，从而使 Au 氧化和 CO 解离的整个过程在能量上是有利的。我们的结果表明，对于 Au/Fe(2)O(3)，存在一种涉及原子 C 和 O 表面物种的 CO 氧化途径，该途径与文献中广泛讨论的碳酸氢盐机制同时存在。然而，对于 Au/ZnO，这种次要途径是不存在的。
