Evgeny Smirnov | ITMO University (original) (raw)
Papers by Evgeny Smirnov
Journal of Electroanalytical Chemistry, Jun 1, 2018
Metal oxide based pH sensors are used in various applications, especially when the conventional g... more Metal oxide based pH sensors are used in various applications, especially when the conventional glass electrode is unsuitable due to its fragility or when the applications require disposable sensors, e.g. for biomedical, clinical or food process monitoring. Generally, such pH sensors are produced by thermal oxidation or electrochemical deposition, neither suited for mass production nor miniaturization. Herein, we report on the fabrication of reliable and sensitive pH sensors based on the nano-assembly of iridium oxide (IrO x) nanoparticles and polydiallyldimethylammonium (PDDA) polymer layers. Such potentiometric sensors were very reproducibly fabricated on a large-scale via a layer-by-layer inkjet printing (LbL IJP) methodology. The obtained results indicated the ability of the LbL IJP technique to easily manipulate the NP coverage by the number of printed bilayers, leading to a swift sensor optimization. Open-circuit potentials were recorded to evaluate the pH sensitivity, response time, and reproducibility of the pH electrodes, which exhibit a rapid, linear and near-Nernstian pH response of about 59 mV/pH. Moreover, an RSD of 0.6% for five different electrodes from the same printing batch showed the excellent reproducibility of the IJP process with a correlation coefficient of 0.99 for all measurements. The insights gained in this study could be the basis for a new approach of developing scalable, patterned and flexible pH sensors with improved performance and a wide range of applications.
Journal of Physical Chemistry Letters, Jul 20, 2017
Redox electrocatalysis (catalysis of electron-transfer reactions by floating conductive particles... more Redox electrocatalysis (catalysis of electron-transfer reactions by floating conductive particles) is discussed from the point-of-view of Fermi level equilibration, and an overall theoretical framework is given. Examples of redox electrocatalysis in solution, in bipolar configuration, and at liquid−liquid interfaces are provided, highlighting that bipolar and liquid−liquid interfacial systems allow the study of the electrocatalytic properties of particles without effects from the support, but only liquid−liquid interfaces allow measurement of the electrocatalytic current directly. Additionally, photoinduced redox electrocatalysis will be of interest, for example, to achieve water splitting.
Faraday Discussions, 2017
Faraday Discussions, 2017
Control over the physical properties of nanoparticle assemblies at a liquid-liquid interface is a... more Control over the physical properties of nanoparticle assemblies at a liquid-liquid interface is a key technological advancement to realize the dream of smart electrovariable nanosystems. Electrified interfaces, such as the interface between two immiscible electrolytes solutions (ITIES), are almost an ideal platform for realizing this dream. Here, we show that the Galvani potential difference across soft interfaces can be effectively used to manipulate: (i) the reactivity of gold nanoparticle assemblies through varying the Fermi level (both chemically and electrochemically); (ii) the location distribution of the nanoparticles at the liquid-liquid interface. In the first case, in addition to our previous studies on electron transfer reactions (ET) across the ITIES, we used intensity modulated photocurrent spectroscopy (IMPS) to study the kinetics of photo-induced electrochemical reactions at the ITIES. As expected, the direct adsorption of gold nanoparticles at the interface modifies the kinetics of the ET reaction (socalled, interfacial redox electrocatalysis), however it did not lead to an increased photocurrent by "plasmonic enhancement". Rather, we found that the product separation depends on double layer effects while the product recombination is controlled by the Galvani potential difference between the two phases. In the second case, we demonstrated that polarizing the ITIES caused migration of gold nanoparticles from the middle region of the cell to its periphery. We called such systems "Marangoni-type shutters". This type of electrovariable plasmonic system did not experience diffusion limitation in terms of the adsorption/ desorption of nanoparticles and the entire movement of nanoparticle assemblies happened almost instantly (within a second). It opens a fresh view on electrovariable plasmonics and presents new opportunities to create smart nanosystems at the ITIES driven with an electric field.
Journal of Physical Chemistry C, Jul 22, 2018
Chaotropes such as urea can break the structure of water, weakening the hydrophobic effect and re... more Chaotropes such as urea can break the structure of water, weakening the hydrophobic effect and reducing aggregation. Here, we investigated how the addition of urea affects the transfer of ions and cationic dyes across the interface between immiscible electrolyte solutions, both water-1,2-dichloroethane and water-trifluorotoluene. For most cations, their half-wave potential of transfer shifted toward more negative values, indicating that it is easier to transfer these ions from the aqueous phase with urea to the organic phase, showing that the addition of urea decreases the solvation of ions in the aqueous phase. However, the half-wave potentials for a series of cationic phenothiazine dyes shifted toward more positive potentials, indicating improved solvation in urea solution. The effect of urea was investigated also by differential capacitance and electrocapillary curves, as well as by molecular dynamics simulations. Finally, electrochemistry at liquid−liquid interfaces allows determination of the transfer energies of ions between water and aqueous solutions of urea via a thermodynamic cycle.
Faraday discussions, Jan 4, 2017
Langmuir, Feb 13, 2018
In this study, we propose a simple shake-flask method to produce micronsize colloidosomes from a ... more In this study, we propose a simple shake-flask method to produce micronsize colloidosomes from a liquid−liquid interface functionalized with a gold nanoparticle (AuNP) film. A step-by-step extraction process of an organic phase partially miscible with water led to the formation of raspberry-like structures covered and protected by a gold nanofilm. The distinctive feature of the prepared colloidosomes is a very thin shell consisting of small AuNPs of 12 or 38 nm in diameter instead of several hundred nanometers reported previously. The interesting and remarkable property of the proposed approach is their reversibility: the colloidosomes may be easily transformed back to a nanofilm state simply by adding pure organic solvent. The obtained colloidosomes have a broadband absorbance spectrum, which makes them of great interest in applications such as photothermal therapy, surface-enhanced Raman spectroscopy studies, and microreactor vesicles for interfacial electrocatalysis. ■ EXPERIMENTAL METHODS Chemicals. Tetrachloroauric acid (HAuCl 4 , 99.9%) and TTF were received from Aldrich. Citrate trisodium dihydrate (Na 3 C 6 H 5 O 7 • 2H 2 O) was purchased from Fluka. Silver nitrate (AgNO 3) was bought from Chempur and ascorbic acid (C 6 H 8 O 6) from Riedel-de-Haen. MeNO 2 was purchased from Sigma-Aldrich. All chemicals were used as received without further purification. In all experiments, Millipore water (18.2 MΩ cm) was used.
Electrochimica Acta, Oct 1, 2019
All redox flow batteries suffer from low energy storage density in comparison with conventional L... more All redox flow batteries suffer from low energy storage density in comparison with conventional Li-ion batteries. However, this issue can be mitigated by utilization of solid energy storage materials to enhance the energy storage capacity. In this paper we demonstrate the utilization of copper hexacyanoferrate (CuHCF) Prussian blue analogue for this purpose, coupled with N,N,N-2,2,6,6-heptamethylpiperidinyl oxy-4-ammonium chloride (TEMPTMA) as a soluble redox mediator to target the redox transitions of the solid material. In this case, indirect charging and discharging of a solid material suspended in the electrolyte by electrochemically oxidized/reduced TEMPTMA was observed by chronoamperometry. Secondly, electrochemistry of different CuHCF composites with carbon black and multi-walled carbon nanotubes investigated, highlighting that the high conductivity of the solid energy storage materials is crucial to access the maximal charge storage capacity of the solid material. Finally, a CuHCF-TEMPTMA/Zn aqueous redox flow battery achieved stable cycling performances with high coulombic efficiency of 95% and volumetric capacity of 350 C mL-1 .
Emulsification of immiscible two-phase fluids, i.e., one condensed phase dispersed homogeneously ... more Emulsification of immiscible two-phase fluids, i.e., one condensed phase dispersed homogeneously as tiny droplets in an outer continuous medium, plays a key role in medicine, food, chemical separations, cosmetics, fabrication of micro- and nanoparticles and capsules, and dynamic optics. Herein, we demonstrate that water clusters/droplets can be formed in an organic phase via the spontaneous assembling of ionic bilayers. We term these clusters ionosomes, by analogy with liposomes where water clusters are encapsulated in a bilayer of lipid molecules. The driving force for the generation of ionosomes is a unique asymmetrical electrostatic attraction at the water/oil interface: small and more mobile hydrated ions reside in the inner aqueous side, which correlate tightly with the lipophilic bulky counterions in the adjacent outer oil side. These ionosomes can be formed through electrochemical (using an external power source) or chemical (by salt distribution) polarization at the liquid-liquid interface. The charge density of the cations, the organic solvent, and the synergistic effects between tetraethylammonium and lithium cations, all affecting the formation of ionosomes, were investigated. These results clearly prove that a new emulsification strategy is developed providing an alternative and generic platform, besides the canonical emulsification procedure with either ionic or nonionic surfactants as emulsifiers. Finally, we also demonstrate the detection of individual ionosomes via single-entity electrochemistry.
Assemblies of Gold Nanoparticles at Liquid-Liquid Interfaces, 2018
In this chapter, we would highlight the critical role of the interfacial tension and three-phase ... more In this chapter, we would highlight the critical role of the interfacial tension and three-phase contact angle in self-assembly process of gold nanoparticles at a liquid–liquid interface. We demonstrate that gold nanoparticles can spontaneously self-assemble at bare propylene carbonate–water interface upon vigorous shaking, due to the extremely low interfacial tension. However, particles are transferred through the interface in the presence of tetrathiafulvalene molecules.
This Chapter highlights the perspectives to realize the potential of MeLLD-type gold nanoparticle... more This Chapter highlights the perspectives to realize the potential of MeLLD-type gold nanoparticle films at liquid-liquid interface. Among them are: microencapsulation for drug-delivery systems and microreactors; transfer of nanofilms from LLI to a solid interface for reusable SERS-substrates and covering large areas with nanoparticles films for various purposes; conductance and thermal properties of nanofilms to use nanofilms for direct writing of conductive tracks with self-terminating welding process; liquid mirrors at water-air interface and electrically driven Maragoni-type shutters.
This chapter illustrates a detailed study of optical and morphological properties of lustrous sel... more This chapter illustrates a detailed study of optical and morphological properties of lustrous self-healing metal liquid-like nanofilms for different applications (e.g., optical mirrors or filters). Extinction and reflectance of nanofilms were investigated by an integrating sphere in UV, visible and NIR ranges with step-bystep increasing of nanoparticle surface coverage. The interfacial AuNP surface coverage strongly influenced the morphology of the interfacial nanofilms and in turn their maximum reflectance and absorbance. We observed three distinct morphological regimes: (i) smooth 2D monolayers of “floating islands” of AuNPs at low surface coverages, (ii) a mixed 2D/3D regime with the beginnings of 3D nanostructures consisting of small piles of adsorbed AuNPs even at sub-full-monolayer conditions, and, finally, (iii) a 3D regime characterized by the 2D full-monolayer being covered in significant piles of adsorbed AuNPs. Also, comparison of optical properties of nanofilms at differ...
Assemblies of Gold Nanoparticles at Liquid-Liquid Interfaces, 2018
This Chapter is fully devoted to experimental procedures, to synthesize and analyze assemblies of... more This Chapter is fully devoted to experimental procedures, to synthesize and analyze assemblies of nanoparticles and to instrumentation techniques used in this work.
Journal of Electroanalytical Chemistry, Jun 1, 2018
Metal oxide based pH sensors are used in various applications, especially when the conventional g... more Metal oxide based pH sensors are used in various applications, especially when the conventional glass electrode is unsuitable due to its fragility or when the applications require disposable sensors, e.g. for biomedical, clinical or food process monitoring. Generally, such pH sensors are produced by thermal oxidation or electrochemical deposition, neither suited for mass production nor miniaturization. Herein, we report on the fabrication of reliable and sensitive pH sensors based on the nano-assembly of iridium oxide (IrO x) nanoparticles and polydiallyldimethylammonium (PDDA) polymer layers. Such potentiometric sensors were very reproducibly fabricated on a large-scale via a layer-by-layer inkjet printing (LbL IJP) methodology. The obtained results indicated the ability of the LbL IJP technique to easily manipulate the NP coverage by the number of printed bilayers, leading to a swift sensor optimization. Open-circuit potentials were recorded to evaluate the pH sensitivity, response time, and reproducibility of the pH electrodes, which exhibit a rapid, linear and near-Nernstian pH response of about 59 mV/pH. Moreover, an RSD of 0.6% for five different electrodes from the same printing batch showed the excellent reproducibility of the IJP process with a correlation coefficient of 0.99 for all measurements. The insights gained in this study could be the basis for a new approach of developing scalable, patterned and flexible pH sensors with improved performance and a wide range of applications.
Journal of Physical Chemistry Letters, Jul 20, 2017
Redox electrocatalysis (catalysis of electron-transfer reactions by floating conductive particles... more Redox electrocatalysis (catalysis of electron-transfer reactions by floating conductive particles) is discussed from the point-of-view of Fermi level equilibration, and an overall theoretical framework is given. Examples of redox electrocatalysis in solution, in bipolar configuration, and at liquid−liquid interfaces are provided, highlighting that bipolar and liquid−liquid interfacial systems allow the study of the electrocatalytic properties of particles without effects from the support, but only liquid−liquid interfaces allow measurement of the electrocatalytic current directly. Additionally, photoinduced redox electrocatalysis will be of interest, for example, to achieve water splitting.
Faraday Discussions, 2017
Faraday Discussions, 2017
Control over the physical properties of nanoparticle assemblies at a liquid-liquid interface is a... more Control over the physical properties of nanoparticle assemblies at a liquid-liquid interface is a key technological advancement to realize the dream of smart electrovariable nanosystems. Electrified interfaces, such as the interface between two immiscible electrolytes solutions (ITIES), are almost an ideal platform for realizing this dream. Here, we show that the Galvani potential difference across soft interfaces can be effectively used to manipulate: (i) the reactivity of gold nanoparticle assemblies through varying the Fermi level (both chemically and electrochemically); (ii) the location distribution of the nanoparticles at the liquid-liquid interface. In the first case, in addition to our previous studies on electron transfer reactions (ET) across the ITIES, we used intensity modulated photocurrent spectroscopy (IMPS) to study the kinetics of photo-induced electrochemical reactions at the ITIES. As expected, the direct adsorption of gold nanoparticles at the interface modifies the kinetics of the ET reaction (socalled, interfacial redox electrocatalysis), however it did not lead to an increased photocurrent by "plasmonic enhancement". Rather, we found that the product separation depends on double layer effects while the product recombination is controlled by the Galvani potential difference between the two phases. In the second case, we demonstrated that polarizing the ITIES caused migration of gold nanoparticles from the middle region of the cell to its periphery. We called such systems "Marangoni-type shutters". This type of electrovariable plasmonic system did not experience diffusion limitation in terms of the adsorption/ desorption of nanoparticles and the entire movement of nanoparticle assemblies happened almost instantly (within a second). It opens a fresh view on electrovariable plasmonics and presents new opportunities to create smart nanosystems at the ITIES driven with an electric field.
Journal of Physical Chemistry C, Jul 22, 2018
Chaotropes such as urea can break the structure of water, weakening the hydrophobic effect and re... more Chaotropes such as urea can break the structure of water, weakening the hydrophobic effect and reducing aggregation. Here, we investigated how the addition of urea affects the transfer of ions and cationic dyes across the interface between immiscible electrolyte solutions, both water-1,2-dichloroethane and water-trifluorotoluene. For most cations, their half-wave potential of transfer shifted toward more negative values, indicating that it is easier to transfer these ions from the aqueous phase with urea to the organic phase, showing that the addition of urea decreases the solvation of ions in the aqueous phase. However, the half-wave potentials for a series of cationic phenothiazine dyes shifted toward more positive potentials, indicating improved solvation in urea solution. The effect of urea was investigated also by differential capacitance and electrocapillary curves, as well as by molecular dynamics simulations. Finally, electrochemistry at liquid−liquid interfaces allows determination of the transfer energies of ions between water and aqueous solutions of urea via a thermodynamic cycle.
Faraday discussions, Jan 4, 2017
Langmuir, Feb 13, 2018
In this study, we propose a simple shake-flask method to produce micronsize colloidosomes from a ... more In this study, we propose a simple shake-flask method to produce micronsize colloidosomes from a liquid−liquid interface functionalized with a gold nanoparticle (AuNP) film. A step-by-step extraction process of an organic phase partially miscible with water led to the formation of raspberry-like structures covered and protected by a gold nanofilm. The distinctive feature of the prepared colloidosomes is a very thin shell consisting of small AuNPs of 12 or 38 nm in diameter instead of several hundred nanometers reported previously. The interesting and remarkable property of the proposed approach is their reversibility: the colloidosomes may be easily transformed back to a nanofilm state simply by adding pure organic solvent. The obtained colloidosomes have a broadband absorbance spectrum, which makes them of great interest in applications such as photothermal therapy, surface-enhanced Raman spectroscopy studies, and microreactor vesicles for interfacial electrocatalysis. ■ EXPERIMENTAL METHODS Chemicals. Tetrachloroauric acid (HAuCl 4 , 99.9%) and TTF were received from Aldrich. Citrate trisodium dihydrate (Na 3 C 6 H 5 O 7 • 2H 2 O) was purchased from Fluka. Silver nitrate (AgNO 3) was bought from Chempur and ascorbic acid (C 6 H 8 O 6) from Riedel-de-Haen. MeNO 2 was purchased from Sigma-Aldrich. All chemicals were used as received without further purification. In all experiments, Millipore water (18.2 MΩ cm) was used.
Electrochimica Acta, Oct 1, 2019
All redox flow batteries suffer from low energy storage density in comparison with conventional L... more All redox flow batteries suffer from low energy storage density in comparison with conventional Li-ion batteries. However, this issue can be mitigated by utilization of solid energy storage materials to enhance the energy storage capacity. In this paper we demonstrate the utilization of copper hexacyanoferrate (CuHCF) Prussian blue analogue for this purpose, coupled with N,N,N-2,2,6,6-heptamethylpiperidinyl oxy-4-ammonium chloride (TEMPTMA) as a soluble redox mediator to target the redox transitions of the solid material. In this case, indirect charging and discharging of a solid material suspended in the electrolyte by electrochemically oxidized/reduced TEMPTMA was observed by chronoamperometry. Secondly, electrochemistry of different CuHCF composites with carbon black and multi-walled carbon nanotubes investigated, highlighting that the high conductivity of the solid energy storage materials is crucial to access the maximal charge storage capacity of the solid material. Finally, a CuHCF-TEMPTMA/Zn aqueous redox flow battery achieved stable cycling performances with high coulombic efficiency of 95% and volumetric capacity of 350 C mL-1 .
Emulsification of immiscible two-phase fluids, i.e., one condensed phase dispersed homogeneously ... more Emulsification of immiscible two-phase fluids, i.e., one condensed phase dispersed homogeneously as tiny droplets in an outer continuous medium, plays a key role in medicine, food, chemical separations, cosmetics, fabrication of micro- and nanoparticles and capsules, and dynamic optics. Herein, we demonstrate that water clusters/droplets can be formed in an organic phase via the spontaneous assembling of ionic bilayers. We term these clusters ionosomes, by analogy with liposomes where water clusters are encapsulated in a bilayer of lipid molecules. The driving force for the generation of ionosomes is a unique asymmetrical electrostatic attraction at the water/oil interface: small and more mobile hydrated ions reside in the inner aqueous side, which correlate tightly with the lipophilic bulky counterions in the adjacent outer oil side. These ionosomes can be formed through electrochemical (using an external power source) or chemical (by salt distribution) polarization at the liquid-liquid interface. The charge density of the cations, the organic solvent, and the synergistic effects between tetraethylammonium and lithium cations, all affecting the formation of ionosomes, were investigated. These results clearly prove that a new emulsification strategy is developed providing an alternative and generic platform, besides the canonical emulsification procedure with either ionic or nonionic surfactants as emulsifiers. Finally, we also demonstrate the detection of individual ionosomes via single-entity electrochemistry.
Assemblies of Gold Nanoparticles at Liquid-Liquid Interfaces, 2018
In this chapter, we would highlight the critical role of the interfacial tension and three-phase ... more In this chapter, we would highlight the critical role of the interfacial tension and three-phase contact angle in self-assembly process of gold nanoparticles at a liquid–liquid interface. We demonstrate that gold nanoparticles can spontaneously self-assemble at bare propylene carbonate–water interface upon vigorous shaking, due to the extremely low interfacial tension. However, particles are transferred through the interface in the presence of tetrathiafulvalene molecules.
This Chapter highlights the perspectives to realize the potential of MeLLD-type gold nanoparticle... more This Chapter highlights the perspectives to realize the potential of MeLLD-type gold nanoparticle films at liquid-liquid interface. Among them are: microencapsulation for drug-delivery systems and microreactors; transfer of nanofilms from LLI to a solid interface for reusable SERS-substrates and covering large areas with nanoparticles films for various purposes; conductance and thermal properties of nanofilms to use nanofilms for direct writing of conductive tracks with self-terminating welding process; liquid mirrors at water-air interface and electrically driven Maragoni-type shutters.
This chapter illustrates a detailed study of optical and morphological properties of lustrous sel... more This chapter illustrates a detailed study of optical and morphological properties of lustrous self-healing metal liquid-like nanofilms for different applications (e.g., optical mirrors or filters). Extinction and reflectance of nanofilms were investigated by an integrating sphere in UV, visible and NIR ranges with step-bystep increasing of nanoparticle surface coverage. The interfacial AuNP surface coverage strongly influenced the morphology of the interfacial nanofilms and in turn their maximum reflectance and absorbance. We observed three distinct morphological regimes: (i) smooth 2D monolayers of “floating islands” of AuNPs at low surface coverages, (ii) a mixed 2D/3D regime with the beginnings of 3D nanostructures consisting of small piles of adsorbed AuNPs even at sub-full-monolayer conditions, and, finally, (iii) a 3D regime characterized by the 2D full-monolayer being covered in significant piles of adsorbed AuNPs. Also, comparison of optical properties of nanofilms at differ...
Assemblies of Gold Nanoparticles at Liquid-Liquid Interfaces, 2018
This Chapter is fully devoted to experimental procedures, to synthesize and analyze assemblies of... more This Chapter is fully devoted to experimental procedures, to synthesize and analyze assemblies of nanoparticles and to instrumentation techniques used in this work.