Understanding Reactivity of Self-Assembled Monolayer-Coated Electrodes: SAM-Induced Surface Reconstruction
Understanding Reactivity of Self-Assembled Monolayer-Coated Electrodes: SAM-Induced Surface Reconstruction
复制标题
DOI：
10.1016/j.electacta.2023.142586
复制
发表时间：
2023-05
影响因子：
6.6
通讯作者：
Francisco W. S. Lucas;Nathanael C. Ramos;D. K. Schwartz;J. Medlin;Adam Holewinski
中科院分区：
文献类型：
--
作者：
Francisco W. S. Lucas;Nathanael C. Ramos;D. K. Schwartz;J. Medlin;Adam Holewinski
硫醇盐自组装单分子膜（SAMs）通常用于修饰表面性质，包括催化活性。这些自组装膜还可以诱导某些金属表面的重构。在这里，我们表明，通过形成和随后从Au多晶电催化剂中去除硫醇盐自组装膜，底层金属表面的不可逆变化可以导致催化性能的显着变化，而不管硫醇盐分子和各种反应物之间可能发生的特定相互作用。使用铅作为表面探针的欠电位沉积，我们发现，在一系列不同的硫醇盐，自组装膜往往会增加Au上的（111）面的比例，但它们同时增加这些和其他方面的缺陷密度。这些变化通常会导致延迟发作，但更高的最大活性对甲酸氧化，这是假设有关的适当的活性位点合奏和中间体的相互作用的密度和站点阻塞羟基物种与新产生的缺陷的变化。重建的影响进一步说明通过测量的巴豆醛的电还原的选择性的变化，与重建的催化剂改变有利的产品从丁醛到巴豆醇。因此，复杂的表面重组可能在SAM改性表面的催化行为中发挥重要作用。
Thiolate self-assembled monolayers (SAMs) are often used to modify surface properties, including catalytic activity. These SAMs can also induce reconstruction of some metallic surfaces. Here we show, through formation and subsequent removal of thiolate SAMs from Au polycrystalline electrocatalysts, that irreversible changes to the underlying metal surface can lead to significant changes in catalytic properties, irrespective of specific interactions that might occur between thiolate molecules and various reactants. Using underpotential deposition of Pb as a surface probe, we find that across a range of different thiolates, SAMs tend to increase the proportion of (111)-facets on Au, but they simultaneously increase the defect density upon these and other facets. These changes generally lead to delayed onset but higher maximum activity toward formic acid oxidation, which is hypothesized to relate to changes in both the density of appropriate active site ensembles and interactions of intermediates and site-blocking hydroxyl species with newly generated defects. The impacts of reconstruction are further illustrated through measured shifts in selectivity for electroreduction of crotonaldehyde, with reconstructed catalysts changing the favored product from butanal to crotyl alcohol. Thus, complex surface reorganization may play a significant role in the catalytic behaviors of SAM-modified surfaces.