Single‐Molecule Measurement of Adsorption Free Energy at the Solid–Liquid Interface. Issue 41 (30th August 2019)

• Record Type: Journal Article
• Authors: Zhan, Chao; Wang, Gan; Zhang, Xia‐Guang; Li, Zhi‐Hao; Wei, Jun‐Ying; Si, Yu; Yang, Yang; Hong, Wenjing; Tian, Zhong‐Qun
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 41(2019)
• Page Start: 14534
• Page End: 14538
• Publication Date: 2019-08-30
• Subjects: adsorption free energy -- break junctions -- interfaces -- molecular electronics -- single-molecule conductance; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201907966
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Adsorption plays a critical role in surface and interface processes. Fractional surface coverage and adsorption free energy are two essential parameters of molecular adsorption. However, although adsorption at the solid–gas interface has been well‐studied, and some adsorption models were proposed more than a century ago, challenges remain for the experimental investigation of molecular adsorption at the solid–liquid interface. Herein, we report the statistical and quantitative single‐molecule measurement of adsorption at the solid–liquid interface by using the single‐molecule break junction technique. The fractional surface coverage was extracted from the analysis of junction formation probability so that the adsorption free energy could be calculated by referring to the Langmuir isotherm. In the case of three prototypical molecules with terminal methylthio, pyridyl, and amino groups, the adsorption free energies were found to be 32.5, 33.9, and 28.3 kJ mol −1, respectively, which are consistent with DFT calculations. Abstract : Surface measurements with depth : A method for measuring adsorption free energy at the solid–liquid interface was developed on the basis of the inherent link between single‐molecule break junction measurements and the surface coverage of the molecule (see picture). The adsorption free energy measured for amino, methylthio, and pyridyl groups on a gold surface was found to agree quantitatively with theoretical results.