Maintaining the order: 4,4′-bipyridine self-assembled layers on the Bi(111) | ionic liquid interface

Abstract

The organised layer of molecules on a solid surface is at the centre of numerous molecular devices. Although the adsorption of molecules from aqueous electrolytes has been thoroughly investigated, only a limited number of studies have focused on the adsorption from ionic liquid electrolytes. This paper characterises the 4,4′-bipyridine adsorption at the Bi(111) | ionic liquid interface. We combined electrochemical impedance spectroscopy and scanning tunnelling microscopy with density functional theory calculations to gain a comprehensive overview of the interfacial processes. The results show a notable influence of electrode potential and the electrolyte on the 4,4′-bipyridine adsorption behaviour. The formation of organic adlayer on the electrode's surface was demonstrated, while highly organised striated adlayer structure was visualised only in a narrow potential range.