DPhil student Samuel Coles came to visit

In Febuary and March last year I visited Tartu to work with the double layer group on a short term scientific mission funded by COST action MP1306. The aim of my visit was to develop a molecular dynamics setup for performing simulations of boundary film shear. During this mission I worked closely with Dr Vladislav Ivaništšev on developing simulation setups and developing a scripting framework. This works is a three way collaboration between the group in Tartu, The group of my supervisor Prof. Susan Perkin and Prof. Maxim Federov at the University of Strathclyde.

During the STSM I also got to explore both Tartu and Estonia more widly. The beauty and historical interest of the area was a welcome distraction from work, during an otherwise highly productive STSM.

Samuel Coles

STSM of Dr. Iuliia Voroshylova

Dr. Iuliia Voroshylova from the University of Porto came to visit us in March for a short term scientific mission. Thank you for the cooperation and work done here.

Abstract

In this STSM visit molecular dynamic simulations of mixtures of two ionic liquids (ILs) – [EMIM][NTf2] and [EMIM][FEP] – were performed in a wide concentration range near neutral and charged Au(111) and Hg(111) surfaces. The focus of this study was on the electrochemical properties of an ionic liquid mixture at an electrified interface that results from the restructuring of the electrical double layer induced by the applied potential and by the variation of the ionic liquid composition. For this study, the new method of representing of electrodes was developed. This method involves a positioning of an additional layer, composed of tiny charged spheres, in front of the electrode. This allows an effective account of surface charge. The steric effects and the inter-ion interactions in the electrical double layer next to the charged and neutral gold and mercury interfaces were accessed. The main mechanisms of ionic interaction in these mixtures related to the layered structure of the IL at the electrolyte–electrode interface that imposes potential energy barriers for the ions moving the direction normal to the electrode surface was studied.

STSM of Dr. Vladislav Ivaništšev

Our work group member Dr. Vladislav Ivaništšev went to University of Santiago de Compostela, Spain for a short term scientific mission. Thank you for the brilliant work there.

Abstract

In this STSM visit were performed molecular dynamic simulations of mixtures of ionic liquids (ILs) with water, mono- and divalent salts of electrochemical interest both in the bulk and near neutral and charged graphene walls. The focus was on the general trends that determine ionic solvation and solute–electrode interactions in ILs and we show the main mechanisms of ionic solvation in these dense ionic media related to the layered structure of the IL at the electrolyte–electrode interface that imposes potential energy barriers for the ions moving the direction normal to the electrode surface. Specifically, we studied the solvation of mono- and divalent ions in ILs and we also obtained results for structure and single-particle dynamics of mixtures of divalent salts with a 1-butyl-3-methylimidazolium tetrafluoroborate. The effect of salt concentration and of the size and valence of the salt cations on the ionic solvation and on the barriers’ parameters was analyzed. For example, we found that the stronger solvation of Li+ in the ionic liquid leads to a formation of significantly higher interfacial free energy barriers for Li+ to come to the electrode than for K+. Moreover, some preliminary insights were obtained for the interfacial behavior of mixtures of ILs with water, studying the effect of the latter on the structure of the interface under normal and nano-confined conditions.