4,4'-Bipyridine Adsorption on Sb(111) from Ionic Liquid- in Situ STM and EIS Study

Abstract

Room-temperature ionic liquids (RTIL) draw a lot of attention in modern electrochemical research due to their high stability under applied electrode potential, the wide electrochemical window and dual usability as a solvent and an electrolyte RTILs have become very attractive. Molecular self-assembly at solid surfaces, resulting in the formation of nanostructures with well-controlled properties and functionality presents multiple prospective applications in science and technology [2], e.g., the smart tailoring of the structural properties of the functionalized electrodes attracts a lot of attention due to an ability to trigger the specific electrochemical processes.In this study, the in situ scanning tunnelling microscopy (STM) and impedance spectroscopy methods have been applied to study the structure and adsorption properties of the electrochemically polished Sb(111) single crystal electrode | EMImBF4, and EMImBF4 + X% 4,4'-bipyridine (x= 1; 2; 5), interface.During the measurements, atomically flat areas have been observed on the in situ STM images of Sb(111) single crystal electrode surface in EMImBF4 and atomic resolution was obtained. The in situ STM data show that there is no quick surface reconstruction process. The surface structure is stable within the potential region investigated (-0.8 — -0.1 vs. Ag/AgCl|EMImBF4) as it has been shown for inactive electrolyte solutions [3].Additionally, the influence of electrode potential on the adsorption kinetics of 4,4'-bipyridine on Sb(111) has been demonstrated. Within the region of maximal adsorption, the capacitance pits in the differential capacitance vs. electrode potential curves have been observed, depending on the 4,4'-bipyridine concentration [4]. The influence of electrode potential (E) on the adsorption kinetics of 4,4'-BiPy on Sb(111) has been demonstrated. From the in situ STM data it has been found that 4,4’-BP adsorbs in a form of a stripe pattern on antimony single crystal electrodes.AcknowledgementsThis work was supported by Estonian Research Council grants PUT PSG249 and RSG676, and by the EU through the European Regional Development Fund under project TK141 (2014-2020.4.01.15-0011).