
Liis SiinorUniversity of Tartu
Liis Siinor
PhD
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59
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Introduction
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August 2010 - present
Publications
Publications (59)
In this study, electrochemical impedance spectroscopy and in situ STM measurements have been used to investigate the interface between a Cd(0001) single-crystal electrode and an ionic liquid electrolyte containing an organic additive. The addition of 4,4ʹ-bipyridine clearly influenced the interfacial structure and properties by forming an adlayer o...
The electrochemistry nowadays has many faces and challenges. Although the focus has shifted from fundamental electrochemistry to applied electrochemistry, one needs to acknowledge that it is impossible to develop and design novel green energy transition devices without a comprehensive understanding of the electrochemical processes at the electrode...
Self-assembled monolayers (SAMs) have significant importance in many modern applications ¹⁻² . The properties of SAMs depend on many aspects, such as the characteristics of individual molecules, forming the monolayer; by the interactions between these molecules; and SAM interactions with the electrolyte; the crystalline surface of the substrate; et...
The self-assembly of adsorbed molecules into structured adlayers on the electrode’s surface provides a straightforward way to modify the interface. Moreover, the formation and properties of the formed adlayers can be controlled by the applied potential, which offers fascinating prospects for the development of molecular switches ¹ , thin film trans...
J.M. Lehn stated in his Nobel prize lecture in 1988 that supramolecular chemistry is the chemistry of the intermolecular bond, covering the structure and functions of entities formed by the association of two or more chemical species [1]. The adsorption of organic molecules is the net result of the interactions between the molecules and the two pha...
Room temperature ionic liquids (RTIL) have had a lot of attention in modern chemical 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 in the field of applied electrochemistry and modern energetics [1]. Molecul...
Self-assembled monolayers (SAMs) have significant importance in many modern applications ¹⁻² . The characteristics of SAMs depend on many aspects, like the characteristics of individual molecules, forming the monolayer; by the interactions between these molecules; and by SAM interactions with the electrolyte; the crystalline surface of the substrat...
In this study, it has been shown that the ordering of organic molecules is not limited to a highly organised self-assembled monolayer on the electrode's surface. At the interface between semi-metallic Sb(111) electrode and ionic liquid with 4,4’-bipyridine addition, two distinctive stacked adsorbed layers upon each other have been identified by app...
The interface between semi-metallic Sb(111) electrode and ionic liquid with 4,4’-bipyridine addition has been studied. Using in situ scanning tunnelling microscopy and electrochemical impedance spectroscopy, the desorption of 4,4’-bipyridine was demonstrated and a dense underlying structure, formed below a sparse self-assembled monolayer, was visua...
Estonian phosphorite ore contains trace amounts of rare earth elements (REEs), many other d-metals, and some radioactive elements. Rare earth elements, Mo, V, etc. might be economically exploitable, while some radioactive and toxic elements should be removed before any other downstream processing for environmental and nutritional safety reasons. Al...
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...
Electrical double layer characteristics and specific adsorption of anions at Bi and Cd single crystal planes from aprotic and other non-aqueous electrolytes, as well as mixtures of surface-inactive and surface-active ionic liquids have been studied and analysed. Strong influence of sp-metal electronic characteristics (concentration of charge carrie...
The adsorption of added 2,2′-bipyridine (2,2′-BP) from 1-ethyl-2,3-dimethyl imidazolium bis(trifluoromethanesulfonyl)imide (EMMImNTf2) at an Au(111) electrode has been investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Addition of 2,2′-BP to the ionic liquid clearly modifies the interfacial region as a resu...
Influence of the iodide ions adsorption on the in situ measured X-ray photoelectron spectra of C 1s, N 1s, B 1s, F 1s and I 3d photoelectrons, indicating the changes in the chemical composition taking place at the carbon (C) | 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) + 1-ethyl-3-methylimidazolium iodide mixed ionic liquids interface,...
Influence of chemical composition of ionic liquids and their mixtures on the electrical double layer characteristics of the cupercapacitors (EDLC) has been studied by cyclic voltammetry, electrochemical impedance spectroscopy, constant current charge-discharge and constant power discharge methods. It has been shown that addition of 1-ethyl-3-methyl...
Specific adsorption of iodide ions has been investigated in our research-group for a long time in different aqueous and classical organic solvents [1]. Recently we have showed how the iodide ions behave in different ionic liquids (ILs) mixtures and demonstrated the influence of specifically adsorbed anion on the electrochemical behaviour of Bi|RTIL...
Room temperature ionic liquids (RTILs) are non-conventional electrolytes that have been under intensive investigation in recent years. Due to their unique physical properties they are interesting media to study at fundamental level and in novel electrochemical devices. [1-4]
Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) m...
The development of novel devices for energy recuperation and storage systems is of paramount importance for the realization of an energetically sustainable society. Capacitors play a huge role in mentioned complexes, being assumed as versatile devices for power applications. Ionic liquids (IL) have been tabbed as “designer electrolytes”, thus offer...
Electrochemical characterization of the interface between Bi(111) surface and ionic liquid mixtures of 1-ethyl-3-methylimidazolium tetrafluoroborate with 1-ethyl-3-methylimidazolium bromide (EMImBF 4 + x% EMImBr) has been evaluated by using the electrochemical impedance spectroscopy, cyclic voltammetry methods and density functional theory calculat...
The electrochemical behavior of RTIL mixtures containing 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and 1-ethyl-3-methylimidazolium iodide were characterized by using cyclic voltammetry and electrochemical impedance spectroscopy methods. The capacitance values of the system at potentials mor...
The Bi(111) | 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) interface has been studied by in situ scanning tunnelling microscopy (STM), cyclic voltammetry and impedance spectroscopy methods within the electrode potential region from − 1.2 V to 0.0 V (vs. Ag | AgCl in EMImBF4) for 60 h. The Bi(111) | EMImBF4 interface is ideally polarisabl...
The in situ scanning tunneling microscopy (STM) and electrochemical impedance spectroscopy studies of electrochemically polished Cd(0001) electrode have been performed in the 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) ionic liquid within electrode potential region from - 1.6 V to - 0.9 V (vs. Ag|AgCl|EMImBF4). The in situ STM data show...
In situ scanning tunneling microscopy (STM), cyclic voltammetry and electrochemical impedance spectroscopy methods have been applied to study the adsorption of 2,2′−bipyridine (2,2′−BP) on Sb(111) single crystal electrode surface from 1−ethyl−3−methylimidazolium tetrafluoroborate + 1% 2,2′−BP solution. Influence of the Sb(111) electrode potential o...
Ionic liquids as electrolytes for modern electrochemical energy conversion/storage devices (electrochemical double layer capacitors (EDLC), hybrid capacitors, batteries, etc.) have been intensively investigated over the past few years. However, still the kinetics of formation/rearrangement of the electrical double layer (edl) between electrode and...
In recent years, application of ionic liquids as electrolytes in electrochemical devises has become more and more routine. Indeed, non-aqueous electrolytes can provide higher cell potential without decomposing. For electrochemical double layer capacitors (EDLCs) the widening of the cell potential increases exponentially the energy and power densiti...
As the global energy need is in a constant growth new and more effective ways of energy production and storage have to be developed. Electrical double-layer capacitors (EDLC) are widely discussed and some even used as energy storage devices due to their high power densities and good cycling stability. However, as a drawback they often suffer from l...
Room temperature ionic liquids (RTILs) can sustain substantially higher cell potentials (Δ E ) in electrochemical cells without decomposing. For electrochemical double layer capacitors (EDLCs) the widening of the cell potential increases exponentially the energy and power densities. RTILs can be use as electrolytes in modern electrochemical energy...
Recently studies of room temperature ionic liquids (RTIL) have had a lot of attention in modern chemical research. Due to their high stability under applied potential, the wide electrochemical window and dual usability as solvent and electrolyte RTILs have become very attractive in the field of applied electrochemistry and modern energetics [1].
Th...
The need for alternative high energy and power density energy sources has led scientists to study extensively the electrochemical energy conversion/storage devices such as electrochemical double layer capacitors (EDLC), batteries, fuel cells, etc. The values of power and energy densities of EDLC depend strongly on the properties of the electrode ma...
The need for alternative high energy and power density energy sources has led scientists to study extensively the electrochemical energy conversion/storage devices such as electrochemical double layer capacitors (EDLC), batteries, fuel cells, etc. The values of power and energy densities of EDLC depend strongly on the properties of the electrode ma...
Formation of an interfacial structure at an electrochemically polished Bi(111) surface in 1 wt.% 1-ethyl-3-methylimidazolium iodide + 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid mixture has been analysed using the high-resolution in situ electrochemical scanning tunneling microscopy, cyclic voltammetry and electrochemical impedance m...
The electrochemical behavior and characteristics of the interface between Bi(111) and 1-ethyl-3-methylimidazolium iodide solution in 1-ethyl-3-methylimidazolium tetrafluoroborate with variable concentrations were investigated by using cyclic voltammetry and electrochemical impedance spectroscopy. The shape of the complex impedance plane plots, the...
The need for alternative high energy and power density energy sources has led scientists to study extensively the electrochemical energy conversion/storage devices such as electrochemical double layer capacitors (EDLC), batteries, fuel cells, etc. The values of power and energy densities of EDLC depend strongly on the properties of the electrode ma...
Applicability of room-temperature ionic liquids (RTILs) as electrolytes for electrical double layer capacitors (EDLCs), so-called supercapacitors and batteries has been discussed in many papers. RTILs have lower conductivity, higher viscosity and thus, narrower low temperature operation limit compared to aqueous and non-aqueous electrolytes. Howeve...
The interface between pyrolytic graphite (PG) and the mixture of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) and 1-ethyl-3-methylimidazolium iodide (EMImI) were electrochemically characterized by using cyclic voltammetry and electrochemical impedance spectroscopy. The addition of EMImI in EMImBF4 influences the region of ideal polarizab...
The influence of addition (5 wt%) of 1-ethyl-3-methylimidazolium iodide (EMImI) in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMEmBF(4)) on the melting point, bulk conductivity and electrochemical properties of the room temperature ionic liquid (RTIL) mixture as an electrolyte in electrical double layer capacitor (EDLC) has been studied using c...
Abstract Interfacial structure of the Bi(1 1 1)textbar1-butyl-4-methylpyridinium tetrafluoroborate (BMPyBF4) interface has been studied applying the in situ scanning tunnelling microscopy (STM), cyclic voltammetry, impedance spectroscopy (EIS), and also computational chemistry methods. Influence of electrode potential and in situ STM scanning condi...
The electrochemical characteristics of the interface between Bi(111) and the mixture of 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-ethyl-3-methylimidazolium iodide were electrochemically characterized by using cyclic voltammetry and electrochemical impedance spectroscopy. The region of ideal polarizability, the formation/rearrangement kine...
The electrochemical characteristics for electrochemically polished Bi(1 1 1) electrode in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) within temperature range from 298 K to 348 K were studied using electrochemical impedance spectroscopy and cyclic voltammetry. The region of ide...
Cyclic voltammetry, electrochemical impedance spectroscopy, and computational chemistry methods have been applied for investigation of electrochemically polished Bi(1 1 1) electrode in 1-butyl-4-methylpyridinium tetrafluoroborate (BMPyBF4) ionic liquid. The region of ideal polarizability, series resistance and capacitance, limiting high-frequency a...
Cyclic voltammetry and electrochemical impedance spectroscopy have been applied for investigation of electrochemically polished Bi(111) electrode in 1-ethyl-3-methyl imidazolium tris(pentafluoroethyl)trifluorophosphate (EMImFAP), 1-ethyl-3-methyl imidazolium tetracyanoborate (EMImTCB) and 1-ethyl-3-methyl imidazolium tetrafluoroborate (EMImBF4) ion...
The influence of the electrode potential on the Bi(111) vertical bar 1-ethyl-3-methylimidazolium tetrafluoroborate interface has been studied by cyclic voltammetry and electrochemical impedance. The weak deviation of the system from capacitive behavior for the ideally flat electrode has been established within the moderate electrode potential regio...
Adsorption of iodide ions at the Bi(111) and Cd(0001) electrodes from the aqueous solutions with constant ionic strength 0.1xM KI + 0.1(1−x)M KF and 0.1xM KI + 0.033(1−x)M K2SO4 has been studied by impedance spectroscopy. It was found that, to a first approximation, the classical Frumkin–Melik–Gaikazyan
equivalent circuit with the slow diffusion-li...
The electrical double layer structure at Bi(111)|1-ethyl-3methyl-imidazolium tetrafluoroborate interface has been studied using cyclic voltammetry and electrochemical impedance. The nearly capacitive behavior has been established in the electrode potential region -0.9 < E < -0.5 V (vs. Ag|AgCl in aq. 4M KCl), where the fractional exponent of the co...
The adsorption of iodide ions from the aqueous solution with constant ionic strength on the Bi(001) single crystal plane electrode has been studied by impedance spectroscopy. The complex impedance plane and Bode plots have been fitted and analyzed, using the non-linear regression analysis method. The probable limiting kinetic steps of the process w...
Erinevate keemiliste protsesside omaduste uurimisega on keemikud tegelenud sajandeid. Füüsikaline elektrokeemia on teadusharu, mis keskendub keemiliste reaktsioonide ja protsesside füüsikaliste omaduste väljaselgitamisele. Antud doktoritöö teemaks on ioonide adsorptioonikineetika uurimine vesilahustes ning ioonsetes vedelikes metallelektroodil, mil...