Departamento de Fisicoquímica, Instituto de Investigaciones en Fisicoquímica de Córdoba (INFIQC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba , X5000 Córdoba, Argentina.
Instituto de Física del Litoral (IFIS) , S3000 Santa Fe, Argentina.
Langmuir. 2017 Dec 5;33(48):13733-13739. doi: 10.1021/acs.langmuir.7b03038. Epub 2017 Nov 14.
The effect of the Au crystalline plane on the adsorption of different thiols and selenols is studied via reductive desorption (RD) and X-ray photoelectron spectroscopy (XPS) measurements. Self-assembled monolayers (SAMs) using aliphatic (ATs) and aromatic thiols (ArTs) on both Au(111) and Au(100) were prepared. The electrochemical stability of these SAMs on both surfaces is evaluated by comparing the position of the RD peaks. The longer the AT chain the more stable the SAM on Au(100) when compared to Au(111). By means of XPS measurements, we determine that the binding energy (BE) of the S 2p signal corresponding to the S atoms at the thiol/Au interface, commonly assigned at 162.0 eV, shifts 0.2 eV from Au(111) to Au(100) for SAMs prepared using thiols with the C* (C atom bonded to S) in sp hybridization, such as ATs. However, when the thiol presents the C* with an sp hybridization, such as in the case of ArTs, the BE remains at 162.0 eV regardless of the surface plane. Selenol-based SAMs were characterized comparatively on both Au(100) and Au(111). Our results show that selenol SAMs become even more electrochemically stable on Au(100) with respect to Au(111) than the analogue sulfur-based SAM. According to our results, we suggest that the electronic distribution around the Au-S/Se bond could be responsible for the different structural arrangements reported in the literature (gold adatoms, etc.), which should be dependent on the crystalline face (Au(hkl)-S) and the chemical nature of the environment of the adsorbates (sp-C* vs sp-C* and Au-SR vs Au-SeR).
通过还原脱附（RD）和 X 射线光电子能谱（XPS）测量研究了 Au 晶面对不同硫醇和硒醇吸附的影响。在 Au(111)和 Au(100)上制备了使用脂肪族（ATs）和芳香族硫醇（ArTs）的自组装单层（SAMs）。通过比较 RD 峰的位置来评估这些 SAM 在两个表面上的电化学稳定性。与 Au(111)相比，当 AT 链更长时，Au(100)上的 SAM 更稳定。通过 XPS 测量，我们确定对应于硫醇/Au 界面处 S 原子的 S 2p 信号的结合能（BE）从 Au(111)向 Au(100)移动 0.2 eV，对于使用具有 sp 杂化的 C*（与 S 键合的 C 原子）的硫醇制备的 SAM 是如此，如 ATs。然而，当硫醇呈现出 sp 杂化时，如在 ArTs 的情况下，无论表面平面如何，BE 仍保持在 162.0 eV。在 Au(100)和 Au(111)上比较了基于硒醇的 SAM 的特性。我们的结果表明，与基于硫醇的 SAM 相比，硒醇 SAM 在 Au(100)上的电化学稳定性甚至更高。根据我们的结果，我们建议围绕 Au-S/Se 键的电子分布可能是导致文献中报道的不同结构排列（金原子等）的原因，这应该取决于晶面（Au(hkl)-S）和吸附物的环境化学性质（sp-C* 与 sp-C* 和 Au-SR 与 Au-SeR）。
