Center for Electrochemical Sciences CES, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780, Bochum, Germany.
Analyst. 2012 Feb 7;137(3):631-40. doi: 10.1039/c1an15671c. Epub 2011 Dec 13.
A complementary combination of cyclic voltammetry, impedance spectroscopy and quartz crystal microbalance techniques was used to: (i) control the assembly of a model electrocatalytic system consisting of monolayer and sub-monolayer amounts of Ag and Pb on a Au electrode, (ii) evaluate the system performance for the reduction of NO(3)(-) and (iii) study the disassembly of the electrocatalytic system to explore any changes which occurred during the assembly and/or catalytic stages. Physical models of the electrochemical interface (described in terms of equivalent electric circuits) at all stages are found to be considerably different but consistent with each other. Deposition of the Ag atomic layer on Au is accompanied by spontaneous surface alloying and specific adsorption of anions. In the following, deposition of the Pb atomic layer triggers further alloying in the Ag(ad)/Au layer while perchlorate-ions leave the surface. Approximately 1/3 of the Pb atomic layer on Ag(ad)/Au was found to demonstrate the best activity towards nitrate reduction. The developed experimental approach shows promise for the in situ characterization and control of all the non-stationary stages which are usually of particular importance in electrocatalytic research.
采用循环伏安法、阻抗谱和石英晶体微天平技术的互补组合：(i)控制由单层和亚单层数量的 Ag 和 Pb 在 Au 电极上组成的模型电催化系统的组装，(ii)评估该系统对 NO(3)(-)还原的性能，(iii)研究电催化系统的拆卸，以探索在组装和/或催化阶段发生的任何变化。在所有阶段，电化学界面的物理模型（用等效电路图描述）被发现有很大的不同，但彼此一致。Au 上 Ag 原子层的沉积伴随着自发的表面合金化和阴离子的特异性吸附。随后，Pb 原子层的沉积引发了 Ag(ad)/Au 层中的进一步合金化，而高氯酸盐离子离开表面。在 Ag(ad)/Au 上的约 1/3 的 Pb 原子层被发现对硝酸盐还原具有最佳的活性。所开发的实验方法有望对通常在电催化研究中特别重要的所有非稳态阶段进行原位表征和控制。
