Journal of Chemical Technology and Metallurgy, Jan 3, 2024
The electrochemical behavior of active electrode (anode) materials (AEMs) for lithium-ion battery... more The electrochemical behavior of active electrode (anode) materials (AEMs) for lithium-ion battery (LIB), prepared with Sn-Co powders electrodeposited in three different current modes, was investigated. It is shown that AEM with Sn-Co powder, obtained in constant-potential mode, has the highest tin content (82.1 wt. %) and the best performance and stability in operation. The anode material, made with this Sn-Co powder, shows a first-cycle charge capacity of 450 mAh g-1, which decreases to 295 mAh g-1 for 10 battery cycles at a current load of 0.8 mA (0.1C). The data also showed that the AEM with Sn-Co powder, deposited in pulse-potential mode, which has the lowest tin content (24.5 wt. % Sn) but the highest dispersity compared to the other powders tested, shows better performance than that of a powder with a tin content of 68.6 wt. %, obtained in constant-current mode. It can be concluded that for the high electrochemical activity of the anode materials, prepared with Sn-Co powders, both the high tin content and the high dispersity and morphological uniformity of the powders are of great importance.
In the past 20 years Microbial fuel cells (MFCs) have been extensively studied regarding the poss... more In the past 20 years Microbial fuel cells (MFCs) have been extensively studied regarding the possibility of transforming organic waste directly into electricity. There are significant differences between MFCs and conventional low temperature Fuel Cells (FCs), which make MFCs attractive: biotic catalyst at the anode; the anodic fuel is complex organic waste; MFCs operate under mild reaction conditions (neutral pH, temperature and pressure), close to ambient levels as optimum. Like chemical fuel cells, MFCs are composed of anode and cathode. Oxygen is an ideal electron acceptor for MFCs because of its high redox potential, availability, and sustainability. However, the Oxygen Reduction Reaction (ORR) is kinetically sluggish, resulting in a large proportion of potential loss. Also, working conditions are quite different because of the type of complex media in which MFCs operate. In order to overcome these limitations, catalysts are often used to lower the overpotentials and accelerate the kinetics of the oxygen reduction reaction. One of the main challenges is the development of efficient and stable cathode catalysts for MFCs. By far, Pt and Pt-based catalysts (PGMs) have been extensively used, due to their catalytic efficiency in gas-diffusion electrodes. But the high cost and low durability have significantly lowered their utilization in MFCs. A variety of non-precious metal catalysts have been developed for MFC applications including carbon-based catalysts, carbon supported composite catalysts, Me-based catalysts and biocatalysts. It is supposed that the ORR catalyst used for wastewater treatment in MFCs is simple to synthesize, cost-effective, durable after long-term operation in wastewater, tolerant to poisoning and able to restore catalytic activity after cleaning. In this regard carbon-based catalyst may be the most promising candidate for practical applications. This study reviews different carbon-based ORR catalysts for MFC applications for wastewater treatment and energy recovery.
Physica Status Solidi A-applications and Materials Science, Mar 6, 2021
Soot is used as an electrode material for possible supercapacitance applications. The carbonaceou... more Soot is used as an electrode material for possible supercapacitance applications. The carbonaceous product is collected from a domestic heating system and possesses a naturally developed high surface area, which is one of the key requirements for such applications. The low‐molecular‐weight compounds in the soot are evaporated and carbonized by heat treatment of the samples in the range 400–800 °C. The heating at different temperatures causes different degrees of carbonization, functional groups removal, and samples’ stabilization. The capacitance is compared of prototypes with electrodes made from materials treated at different temperatures. The prototype samples are investigated by Fourier transform infrared spectroscopy and transmission electron microscopy, revealing sequentially removed functional groups and a variety of carbon structures, such as graphene sheets, monocrystalline carbon particles, and onion‐like structures.
Journal of The Electrochemical Society, Feb 24, 2022
Carbon-based porous materials are most widely used for mMicrobial fuel cells based on their uniqu... more Carbon-based porous materials are most widely used for mMicrobial fuel cells based on their unique properties facilitating and allowing the development of high surface area electrode. The electrochemically active layer of the electrode was prepared using two types of catalysts: activated carbon (Norit NK) and activated carbon promoted with CoTMPP (AC/CoTMPP). Mobilization of phosphate ions in the liquid phase was observed during the process of livestock manure treatment. From 20 mg l-1 initially, the concentration of dissolved phosphates reached 100 mg l-1 after 96 hours. Increased concentration of ammonium ions in the medium was also observed, indicating ongoing anaerobic degradation and mineralization of the organic matter. The processes taking place in the bio electrochemical reactor used result in recovery of nutrients and production of energy. A maximum current density of 140 µА cm-2 was reached during the MFC operation. The chemical oxygen demand removal rates were relatively high (above 2g O2/L/h) for both differently catalyzed cathode configurations. As widely reported elsewhere, the electrochemical results confirm that a gas-diffusion electrode using activated carbon catalyst is very well suited as a positive electrode for use in bio electrochemical systems.
Development of a standard dosimetric facility with protection against external radiation backgrou... more Development of a standard dosimetric facility with protection against external radiation background for the metrological support of highly sensitive radiation monitoring devices in accordance with the requirements of international standards ..
Powder of α-Fe2O3 (hematite) with particles sizes of about 100 - 200 nm was synthesized by the lo... more Powder of α-Fe2O3 (hematite) with particles sizes of about 100 - 200 nm was synthesized by the low external temperature method (LETM) using a 1M solution of Fe(NO3)3 9H2O as a starting material.
Tin-graphite composite with 20 wt. % metal content as well as its structural and electrochemical ... more Tin-graphite composite with 20 wt. % metal content as well as its structural and electrochemical characteristics are presented. Synthetic graphite-super flake type-was used as object for the modification experiment. Chemical reduction was applied for the loading process, which was carried out under inert argon atmosphere. Composite with specific morphology and improved electrochemical behavior was prepared. The obtained material shows higher discharge capacity as well as increased initial charge-discharge coulomb efficiency, compared with the unmodified one. The supporting metal morphology, the type of graphite, and the preparation process taken together generally affect the improvement of the electrochemical performance.
1 Institute of Electrochemistry and Energy Systems “Acad. Evgeni Budevski”, Bulgarian Academy of ... more 1 Institute of Electrochemistry and Energy Systems “Acad. Evgeni Budevski”, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., Block 10, 1113 Sofia, Bulgaria. 2 Materials Research Institute, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom. 3 AIT Austrian Institute of Technology GmbH, Giefinggasse 2, 1210 Vienna, Austria.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Vanadium bronzes are attractive materials for rechargeable Libatteries. The electrochemical behav... more Vanadium bronzes are attractive materials for rechargeable Libatteries. The electrochemical behaviour of bronzes strongly depends on the synthesis method due to the particle size of the material.
A low external temperature method (LETM) of active electrode material synthesis for lithium ion b... more A low external temperature method (LETM) of active electrode material synthesis for lithium ion batteries has been proposed. The method consists of a two-step process, which is comprised of drying fine droplets of a solution of the starting compound in a liquid drying agent at 200°C, followed by calcination of the obtained precursor in a fluidised bed at a furnace temperature of 300°C. The method prevents uncontrolled growth of particles during the initial thermal pre-treatment and the final firing process. Lithium manganese spinel has been selected for describing the proposed LETM of synthesis. The properties of the spinel obtained by LETM are compared with those of a spinel obtained by the classical immobilised solid state synthesis at 750°C. On electrochemical cycling, the capacity loss after 100 cycles of the LETM spinel at 11% is significantly lower than that for the spinel prepared by solid state methods (21.5%). However, only 3% difference is seen in the total integral capacity over the 100 cycles between spinels prepared by the different methods.
Carbon coated and titanium substituted lithium vanadium phosphate composites have been successful... more Carbon coated and titanium substituted lithium vanadium phosphate composites have been successfully prepared through a sol-gel method followed by solid state reaction under argon. Li 3 V 1.9 Ti 0.1 (PO 4) 3-C (LVT10PC) and Li 3 V 1.85 Ti 0.15 (PO 4) 3-C (LVT15PC) were investigated using X-ray powder diffraction, thermal analysis, transmission electron microscopy, cyclic voltammetry and galvanostatic tests. Different models for the solid solution mechanism in this system are discussed. Electrochemical tests, at a charge-discharge rate of 0.2C, in the range 2.8-4.4 V, show that LVT10PC delivers the highest discharge capacity of 121 mA h g-1 and declines to 115.7 mA h g-1 , up to the 60 th cycle, corresponding to a 4.4% loss. At low levels, titanium substitution is found to increase initial discharge capacity, compared to the carbon coated unsubstituted system (LVPC). Further substitution is found to have detrimental effects on initial discharge capacity and cycling behaviour.
A polymerization procedure is presented to increase the molecular weight of hydrocarbons in house... more A polymerization procedure is presented to increase the molecular weight of hydrocarbons in household chimney soot without thermal treatment at high temperatures. Pristine soot was subject to chlorination, with half of it treated with magnesium (Mg-plates) to create random-type Grignard reagents (R-Mg-Cl) in diethyl ether media. Mixing the Grignard reagent and the rest of the halogenated soot material created new C-C bonds, thus increasing the molecular weight of the final product. The obtained stochastically polymerized soot (SPS) was investigated using Raman spectroscopy, FTIR spectroscopy and XPS and was subjected to electrochemical testing as an assembled supercapacitor with a KOH electrolyte. Results show significant carbon structure differences due to the chemical procedures and newly created functional groups in the soot. Such functional groups could increase the capacity of supercapacitors, creating pseudo-capacitance by participating in redox reactions. The results also unv...
Intermetallic (Ni-Sn) nanoparticles are synthesized through a borohydride reduction with NaBH4 in... more Intermetallic (Ni-Sn) nanoparticles are synthesized through a borohydride reduction with NaBH4 in a mixture of aqueous solutions of NiCl2.6H2O and SnCl2.2H2O at mass ratio and Ni:Sn = 45:55. The ratio is chosen in accordance with the Ni-Sn binary system phase diagram. A "template" technique which involves borohydride reduction of intermetallic nanoparticles on a support (carbon foam, graphite, carbon powder) is also used. The samples which are Ni-Sn alloys and carbon-based nanocomposites are studied by scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The samples are electrochemically tested as electrode materials in Li-ion batteries.
Ecological Engineering and Environment Protection, 2021
In the past 20 years Microbial fuel cells (MFCs) have been extensively studied regarding the poss... more In the past 20 years Microbial fuel cells (MFCs) have been extensively studied regarding the possibility of transforming organic waste directly into electricity. There are significant differences between MFCs and conventional low temperature Fuel Cells (FCs), which make MFCs attractive: biotic catalyst at the anode; the anodic fuel is complex organic waste; MFCs operate under mild reaction conditions (neutral pH, temperature and pressure), close to ambient levels as optimum. Like chemical fuel cells, MFCs are composed of anode and cathode. Oxygen is an ideal electron acceptor for MFCs because of its high redox potential, availability, and sustainability. However, the Oxygen Reduction Reaction (ORR) is kinetically sluggish, resulting in a large proportion of potential loss. Also, working conditions are quite different because of the type of complex media in which MFCs operate. In order to overcome these limitations, catalysts are often used to lower the overpotentials and accelerate ...
Carbon-based porous materials are most widely used for mMicrobial fuel cells based on their uniqu... more Carbon-based porous materials are most widely used for mMicrobial fuel cells based on their unique properties facilitating and allowing the development of high surface area electrode. The electrochemically active layer of the electrode was prepared using two types of catalysts: activated carbon (Norit NK) and activated carbon promoted with CoTMPP (AC/CoTMPP). Mobilization of phosphate ions in the liquid phase was observed during the process of livestock manure treatment. From 20 mg l-1 initially, the concentration of dissolved phosphates reached 100 mg l-1 after 96 hours. Increased concentration of ammonium ions in the medium was also observed, indicating ongoing anaerobic degradation and mineralization of the organic matter. The processes taking place in the bio electrochemical reactor used result in recovery of nutrients and production of energy. A maximum current density of 140 µА cm-2 was reached during the MFC operation. The chemical oxygen demand removal rates were relatively ...
NATO Science for Peace and Security Series A: Chemistry and Biology, 2014
The aim of the present work is the synthesis and characterization of novel oxide materials in vie... more The aim of the present work is the synthesis and characterization of novel oxide materials in view of their potential use as active material in lithium ion batteries. Bulk materials from (TiO2)x(V2O5)y(P2O5)100-x-y system, where x = 5, 10, 15 and y = 60, 70, were prepared by means of the melt quenching method. The materials were characterized by physical chemical and electrochemical methods, i.e. X-ray diffraction, infrared spectroscopy and cyclic voltammetry measurements. The electrochemical properties were investigated against metallic lithium as active materials in a half-cell system.
NATO Science for Peace and Security Series B: Physics and Biophysics
Si/C composites have been employed in an attempt to overcome the problems of Si-based negative Li... more Si/C composites have been employed in an attempt to overcome the problems of Si-based negative Li-ion electrodes. The composites were produced by coating, followed by a two-step solid state reaction. Electrodes were prepared therefrom by spreading on a Cu foil. The materials were characterized by SEM and XRD. The Si phase in the composite shows an enhanced crystalline structure compared
Intermetallic Co-Sn nanoparticles have been synthesized through a template borohydride reduction ... more Intermetallic Co-Sn nanoparticles have been synthesized through a template borohydride reduction with NaBH4, using a carbon-containing support in a mixture of aqueous solutions of the corresponding chloride salts (CoCl2.6H2O and SnCl2.2H2O) at mass ratio Co:Sn = 35:65. The ratio is chosen in accordance with the Co-Sn binary system phase diagram. The “template” technique involves reductive precipitation of intermetallic nanoparticles on a support. Fluorinated graphite (CF) and graphite/β-cyclodextrin (Dx) hydrate have been used as supports. Subsequently, carbon polymer-based nanocomposites with Co-Sn nanoparticles have been obtained. The content of the polymer in the obtained nanocomposites varies between the samples. The reductive precipitation was carried out at room temperature and atmospheric pressure. Samples were studied by physic-chemical and electrochemical analyses. The morphology, structure, phase composition and surface element content of the prepared nanocomposites have b...
Journal of Chemical Technology and Metallurgy, Jan 3, 2024
The electrochemical behavior of active electrode (anode) materials (AEMs) for lithium-ion battery... more The electrochemical behavior of active electrode (anode) materials (AEMs) for lithium-ion battery (LIB), prepared with Sn-Co powders electrodeposited in three different current modes, was investigated. It is shown that AEM with Sn-Co powder, obtained in constant-potential mode, has the highest tin content (82.1 wt. %) and the best performance and stability in operation. The anode material, made with this Sn-Co powder, shows a first-cycle charge capacity of 450 mAh g-1, which decreases to 295 mAh g-1 for 10 battery cycles at a current load of 0.8 mA (0.1C). The data also showed that the AEM with Sn-Co powder, deposited in pulse-potential mode, which has the lowest tin content (24.5 wt. % Sn) but the highest dispersity compared to the other powders tested, shows better performance than that of a powder with a tin content of 68.6 wt. %, obtained in constant-current mode. It can be concluded that for the high electrochemical activity of the anode materials, prepared with Sn-Co powders, both the high tin content and the high dispersity and morphological uniformity of the powders are of great importance.
In the past 20 years Microbial fuel cells (MFCs) have been extensively studied regarding the poss... more In the past 20 years Microbial fuel cells (MFCs) have been extensively studied regarding the possibility of transforming organic waste directly into electricity. There are significant differences between MFCs and conventional low temperature Fuel Cells (FCs), which make MFCs attractive: biotic catalyst at the anode; the anodic fuel is complex organic waste; MFCs operate under mild reaction conditions (neutral pH, temperature and pressure), close to ambient levels as optimum. Like chemical fuel cells, MFCs are composed of anode and cathode. Oxygen is an ideal electron acceptor for MFCs because of its high redox potential, availability, and sustainability. However, the Oxygen Reduction Reaction (ORR) is kinetically sluggish, resulting in a large proportion of potential loss. Also, working conditions are quite different because of the type of complex media in which MFCs operate. In order to overcome these limitations, catalysts are often used to lower the overpotentials and accelerate the kinetics of the oxygen reduction reaction. One of the main challenges is the development of efficient and stable cathode catalysts for MFCs. By far, Pt and Pt-based catalysts (PGMs) have been extensively used, due to their catalytic efficiency in gas-diffusion electrodes. But the high cost and low durability have significantly lowered their utilization in MFCs. A variety of non-precious metal catalysts have been developed for MFC applications including carbon-based catalysts, carbon supported composite catalysts, Me-based catalysts and biocatalysts. It is supposed that the ORR catalyst used for wastewater treatment in MFCs is simple to synthesize, cost-effective, durable after long-term operation in wastewater, tolerant to poisoning and able to restore catalytic activity after cleaning. In this regard carbon-based catalyst may be the most promising candidate for practical applications. This study reviews different carbon-based ORR catalysts for MFC applications for wastewater treatment and energy recovery.
Physica Status Solidi A-applications and Materials Science, Mar 6, 2021
Soot is used as an electrode material for possible supercapacitance applications. The carbonaceou... more Soot is used as an electrode material for possible supercapacitance applications. The carbonaceous product is collected from a domestic heating system and possesses a naturally developed high surface area, which is one of the key requirements for such applications. The low‐molecular‐weight compounds in the soot are evaporated and carbonized by heat treatment of the samples in the range 400–800 °C. The heating at different temperatures causes different degrees of carbonization, functional groups removal, and samples’ stabilization. The capacitance is compared of prototypes with electrodes made from materials treated at different temperatures. The prototype samples are investigated by Fourier transform infrared spectroscopy and transmission electron microscopy, revealing sequentially removed functional groups and a variety of carbon structures, such as graphene sheets, monocrystalline carbon particles, and onion‐like structures.
Journal of The Electrochemical Society, Feb 24, 2022
Carbon-based porous materials are most widely used for mMicrobial fuel cells based on their uniqu... more Carbon-based porous materials are most widely used for mMicrobial fuel cells based on their unique properties facilitating and allowing the development of high surface area electrode. The electrochemically active layer of the electrode was prepared using two types of catalysts: activated carbon (Norit NK) and activated carbon promoted with CoTMPP (AC/CoTMPP). Mobilization of phosphate ions in the liquid phase was observed during the process of livestock manure treatment. From 20 mg l-1 initially, the concentration of dissolved phosphates reached 100 mg l-1 after 96 hours. Increased concentration of ammonium ions in the medium was also observed, indicating ongoing anaerobic degradation and mineralization of the organic matter. The processes taking place in the bio electrochemical reactor used result in recovery of nutrients and production of energy. A maximum current density of 140 µА cm-2 was reached during the MFC operation. The chemical oxygen demand removal rates were relatively high (above 2g O2/L/h) for both differently catalyzed cathode configurations. As widely reported elsewhere, the electrochemical results confirm that a gas-diffusion electrode using activated carbon catalyst is very well suited as a positive electrode for use in bio electrochemical systems.
Development of a standard dosimetric facility with protection against external radiation backgrou... more Development of a standard dosimetric facility with protection against external radiation background for the metrological support of highly sensitive radiation monitoring devices in accordance with the requirements of international standards ..
Powder of α-Fe2O3 (hematite) with particles sizes of about 100 - 200 nm was synthesized by the lo... more Powder of α-Fe2O3 (hematite) with particles sizes of about 100 - 200 nm was synthesized by the low external temperature method (LETM) using a 1M solution of Fe(NO3)3 9H2O as a starting material.
Tin-graphite composite with 20 wt. % metal content as well as its structural and electrochemical ... more Tin-graphite composite with 20 wt. % metal content as well as its structural and electrochemical characteristics are presented. Synthetic graphite-super flake type-was used as object for the modification experiment. Chemical reduction was applied for the loading process, which was carried out under inert argon atmosphere. Composite with specific morphology and improved electrochemical behavior was prepared. The obtained material shows higher discharge capacity as well as increased initial charge-discharge coulomb efficiency, compared with the unmodified one. The supporting metal morphology, the type of graphite, and the preparation process taken together generally affect the improvement of the electrochemical performance.
1 Institute of Electrochemistry and Energy Systems “Acad. Evgeni Budevski”, Bulgarian Academy of ... more 1 Institute of Electrochemistry and Energy Systems “Acad. Evgeni Budevski”, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., Block 10, 1113 Sofia, Bulgaria. 2 Materials Research Institute, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom. 3 AIT Austrian Institute of Technology GmbH, Giefinggasse 2, 1210 Vienna, Austria.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Vanadium bronzes are attractive materials for rechargeable Libatteries. The electrochemical behav... more Vanadium bronzes are attractive materials for rechargeable Libatteries. The electrochemical behaviour of bronzes strongly depends on the synthesis method due to the particle size of the material.
A low external temperature method (LETM) of active electrode material synthesis for lithium ion b... more A low external temperature method (LETM) of active electrode material synthesis for lithium ion batteries has been proposed. The method consists of a two-step process, which is comprised of drying fine droplets of a solution of the starting compound in a liquid drying agent at 200°C, followed by calcination of the obtained precursor in a fluidised bed at a furnace temperature of 300°C. The method prevents uncontrolled growth of particles during the initial thermal pre-treatment and the final firing process. Lithium manganese spinel has been selected for describing the proposed LETM of synthesis. The properties of the spinel obtained by LETM are compared with those of a spinel obtained by the classical immobilised solid state synthesis at 750°C. On electrochemical cycling, the capacity loss after 100 cycles of the LETM spinel at 11% is significantly lower than that for the spinel prepared by solid state methods (21.5%). However, only 3% difference is seen in the total integral capacity over the 100 cycles between spinels prepared by the different methods.
Carbon coated and titanium substituted lithium vanadium phosphate composites have been successful... more Carbon coated and titanium substituted lithium vanadium phosphate composites have been successfully prepared through a sol-gel method followed by solid state reaction under argon. Li 3 V 1.9 Ti 0.1 (PO 4) 3-C (LVT10PC) and Li 3 V 1.85 Ti 0.15 (PO 4) 3-C (LVT15PC) were investigated using X-ray powder diffraction, thermal analysis, transmission electron microscopy, cyclic voltammetry and galvanostatic tests. Different models for the solid solution mechanism in this system are discussed. Electrochemical tests, at a charge-discharge rate of 0.2C, in the range 2.8-4.4 V, show that LVT10PC delivers the highest discharge capacity of 121 mA h g-1 and declines to 115.7 mA h g-1 , up to the 60 th cycle, corresponding to a 4.4% loss. At low levels, titanium substitution is found to increase initial discharge capacity, compared to the carbon coated unsubstituted system (LVPC). Further substitution is found to have detrimental effects on initial discharge capacity and cycling behaviour.
A polymerization procedure is presented to increase the molecular weight of hydrocarbons in house... more A polymerization procedure is presented to increase the molecular weight of hydrocarbons in household chimney soot without thermal treatment at high temperatures. Pristine soot was subject to chlorination, with half of it treated with magnesium (Mg-plates) to create random-type Grignard reagents (R-Mg-Cl) in diethyl ether media. Mixing the Grignard reagent and the rest of the halogenated soot material created new C-C bonds, thus increasing the molecular weight of the final product. The obtained stochastically polymerized soot (SPS) was investigated using Raman spectroscopy, FTIR spectroscopy and XPS and was subjected to electrochemical testing as an assembled supercapacitor with a KOH electrolyte. Results show significant carbon structure differences due to the chemical procedures and newly created functional groups in the soot. Such functional groups could increase the capacity of supercapacitors, creating pseudo-capacitance by participating in redox reactions. The results also unv...
Intermetallic (Ni-Sn) nanoparticles are synthesized through a borohydride reduction with NaBH4 in... more Intermetallic (Ni-Sn) nanoparticles are synthesized through a borohydride reduction with NaBH4 in a mixture of aqueous solutions of NiCl2.6H2O and SnCl2.2H2O at mass ratio and Ni:Sn = 45:55. The ratio is chosen in accordance with the Ni-Sn binary system phase diagram. A "template" technique which involves borohydride reduction of intermetallic nanoparticles on a support (carbon foam, graphite, carbon powder) is also used. The samples which are Ni-Sn alloys and carbon-based nanocomposites are studied by scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The samples are electrochemically tested as electrode materials in Li-ion batteries.
Ecological Engineering and Environment Protection, 2021
In the past 20 years Microbial fuel cells (MFCs) have been extensively studied regarding the poss... more In the past 20 years Microbial fuel cells (MFCs) have been extensively studied regarding the possibility of transforming organic waste directly into electricity. There are significant differences between MFCs and conventional low temperature Fuel Cells (FCs), which make MFCs attractive: biotic catalyst at the anode; the anodic fuel is complex organic waste; MFCs operate under mild reaction conditions (neutral pH, temperature and pressure), close to ambient levels as optimum. Like chemical fuel cells, MFCs are composed of anode and cathode. Oxygen is an ideal electron acceptor for MFCs because of its high redox potential, availability, and sustainability. However, the Oxygen Reduction Reaction (ORR) is kinetically sluggish, resulting in a large proportion of potential loss. Also, working conditions are quite different because of the type of complex media in which MFCs operate. In order to overcome these limitations, catalysts are often used to lower the overpotentials and accelerate ...
Carbon-based porous materials are most widely used for mMicrobial fuel cells based on their uniqu... more Carbon-based porous materials are most widely used for mMicrobial fuel cells based on their unique properties facilitating and allowing the development of high surface area electrode. The electrochemically active layer of the electrode was prepared using two types of catalysts: activated carbon (Norit NK) and activated carbon promoted with CoTMPP (AC/CoTMPP). Mobilization of phosphate ions in the liquid phase was observed during the process of livestock manure treatment. From 20 mg l-1 initially, the concentration of dissolved phosphates reached 100 mg l-1 after 96 hours. Increased concentration of ammonium ions in the medium was also observed, indicating ongoing anaerobic degradation and mineralization of the organic matter. The processes taking place in the bio electrochemical reactor used result in recovery of nutrients and production of energy. A maximum current density of 140 µА cm-2 was reached during the MFC operation. The chemical oxygen demand removal rates were relatively ...
NATO Science for Peace and Security Series A: Chemistry and Biology, 2014
The aim of the present work is the synthesis and characterization of novel oxide materials in vie... more The aim of the present work is the synthesis and characterization of novel oxide materials in view of their potential use as active material in lithium ion batteries. Bulk materials from (TiO2)x(V2O5)y(P2O5)100-x-y system, where x = 5, 10, 15 and y = 60, 70, were prepared by means of the melt quenching method. The materials were characterized by physical chemical and electrochemical methods, i.e. X-ray diffraction, infrared spectroscopy and cyclic voltammetry measurements. The electrochemical properties were investigated against metallic lithium as active materials in a half-cell system.
NATO Science for Peace and Security Series B: Physics and Biophysics
Si/C composites have been employed in an attempt to overcome the problems of Si-based negative Li... more Si/C composites have been employed in an attempt to overcome the problems of Si-based negative Li-ion electrodes. The composites were produced by coating, followed by a two-step solid state reaction. Electrodes were prepared therefrom by spreading on a Cu foil. The materials were characterized by SEM and XRD. The Si phase in the composite shows an enhanced crystalline structure compared
Intermetallic Co-Sn nanoparticles have been synthesized through a template borohydride reduction ... more Intermetallic Co-Sn nanoparticles have been synthesized through a template borohydride reduction with NaBH4, using a carbon-containing support in a mixture of aqueous solutions of the corresponding chloride salts (CoCl2.6H2O and SnCl2.2H2O) at mass ratio Co:Sn = 35:65. The ratio is chosen in accordance with the Co-Sn binary system phase diagram. The “template” technique involves reductive precipitation of intermetallic nanoparticles on a support. Fluorinated graphite (CF) and graphite/β-cyclodextrin (Dx) hydrate have been used as supports. Subsequently, carbon polymer-based nanocomposites with Co-Sn nanoparticles have been obtained. The content of the polymer in the obtained nanocomposites varies between the samples. The reductive precipitation was carried out at room temperature and atmospheric pressure. Samples were studied by physic-chemical and electrochemical analyses. The morphology, structure, phase composition and surface element content of the prepared nanocomposites have b...
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