Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands.
Nat Chem. 2011 Dec 11;4(3):177-82. doi: 10.1038/nchem.1221.
In heterogeneous catalysis and electrocatalysis, adsorbed carbon monoxide typically acts as a poison or poisoning intermediate in the oxidation of alcohols. However, gold as an (electro)catalyst often exhibits unexpected properties. Here we show that carbon monoxide irreversibly adsorbed on a Au(111) surface in aqueous alkaline media can act as a promoter for the electrocatalytic oxidation of certain alcohols, in particular methanol. In comparison with bare Au(111), the onset potential for methanol oxidation is significantly lower in the presence of adsorbed CO, and formation of the main methanol oxidation products--formaldehyde and formic acid--is enhanced. By studying the effect of adsorbed CO on the oxidation of other alcohols on gold, we conclude that the presence of adsorbed CO promotes beta-hydrogen elimination, that is, C-H bond breaking. Apart from its importance to gold catalysis, this is an unanticipated example of promotion effects by co-adsorbed small molecules in electrocatalysis.
在多相催化和电催化中，吸附的一氧化碳通常在醇的氧化中作为毒物或中毒中间体。然而，金作为（电）催化剂往往表现出意想不到的性质。在这里，我们表明，在碱性水溶液中吸附在 Au(111)表面上的一氧化碳可以作为某些醇，特别是甲醇的电催化氧化的促进剂。与裸露的 Au(111)相比，在吸附 CO 的存在下，甲醇氧化的起始电位显著降低，并且主要甲醇氧化产物-甲醛和甲酸的形成得到增强。通过研究吸附 CO 对金上其他醇氧化的影响，我们得出结论，吸附 CO 的存在促进了β-氢消除，即 C-H 键断裂。除了对金催化的重要性之外，这也是电催化中共同吸附小分子促进作用的一个意外例子。
