Adsorption of Bipyridine at Single-Crystal Electrode | Ionic Liquid Interface – from Monolayers to Clusters
Authors: Ers Heigo , Siinor Liis , Pikma Piret 
Published: December 2024

The self-assembly of organic molecules into ordered structures on the electrode’s surface offers various options for surface functionalisation. The formation of nanostructures also provides insights into the subtle interplay of various interactions between the electrode, organic adsorbate, and the electrolyte1. The detailed description of adsorption and self-assembly processes thus contributes to the development of molecular wires, junctions, and switches. Various studies have focused on the formation of a hybrid inorganic-organic interface in vacuum or aqueous electrolytes2–5. Using ionic liquids as electrolytes in nanotechnology can be beneficial due to their large variability, low vapour pressure, and good electrochemical stability. Meanwhile, their interfacial properties differ notably from other common solvents.

The given presentation focuses on the adsorption and self-assembly of 4,4’-bipyridine at single-crystal electrode | ionic liquid interface. The use of density functional theory calculations alongside in situ scanning tunnelling microscopy and electrochemical impedance spectroscopy provides a multifaceted description of the 4,4’-bipyridine adsorption. The results show that, although the organic adlayer forms at studied Bi(111)6, Sb(111)7, and Cd(0001)8 electrode surfaces, the adlayer structure varies from highly organised monolayers to clusters. Furthermore, there are notable differences in 4,4’-bipyridine adsorption behaviour from previous aqueous electrolyte studies, highlighting the complex nature of the adsorption and organisation processes at electrode | ionic liquid interfaces9–11.

Acknowledgements

This work was supported by the Estonian Research Council grant PSG249, by the EU through the European Regional Development Fund under project TK141 (2014-2020.4.01.15-0011), by the Estonian Ministry of Education and Research (TK210), by the project “Increasing the knowledge intensity of Ida-Viru entrepreneurship” (ÕÜF12) co-funded by the European Union, and by the Graduate School of Functional materials and technologies receiving funding from the European Regional Development Fund in University of Tartu, Estonia.

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