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Kaido Tammeveski - One of the best experts on this subject based on the ideXlab platform.

  • oxygen reduction on graphene sheets functionalised by anthraquinone Diazonium Compound during electrochemical exfoliation of graphite
    Electrochimica Acta, 2018
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Benjamin Diby Ossonon, Daniel Belanger, Kaido Tammeveski
    Abstract:

    Abstract In this paper, the oxygen reduction reaction (ORR) was studied on anthraquinone (AQ) modified and unmodified graphene sheets in aqueous solutions. AQ-grafted graphene sheets were prepared by one-pot synthesis procedure using electrochemical exfoliation of graphite and in situ spontaneous Diazonium reduction at the same time in 0.1 M H2SO4. Unmodified and AQ-grafted graphene were characterised by thermogravimetric analysis and Raman spectroscopy. Covalent attachment of AQ on graphene was ascertained. The ORR was studied in acidic and alkaline electrolytes by the rotating disc electrode method. In both media, the prepared graphene materials were more active towards the ORR than bare glassy carbon. In alkaline solution, the number of electrons transferred per O2 molecule for AQ-modified and unmodified graphene coated glassy carbon electrodes was higher than two indicating that the formed hydrogen peroxide is partially further reduced. In addition, stability testing of the prepared electrodes during potential cycling yielded a small loss of activity.

  • oxygen reduction on anthraquinone Diazonium Compound derivatised multi walled carbon nanotube and graphene based electrodes
    Electroanalysis, 2017
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Leonard Matisen, Kaido Tammeveski
    Abstract:

    In this work, graphene and multi-walled carbon nanotubes were derivatised with anthraquinone (AQ) groups using spontaneous or electrochemical grafting of Fast Red AL salt. Glassy carbon (GC) electrodes were coated with AQ-modified carbon nanomaterials to study the oxygen reduction reaction (ORR). These nanomaterials were characterised by X-ray photoelectron spectroscopy and multilayer formation of AQ on the electrografted electrodes was observed. All the modified electrodes showed enhanced electrocatalytic activity towards the ORR in alkaline media. High AQ loading on the electrodes was found and the number of electrons transferred per O2 molecule was between 2 and 4. In addition, the stability testing of AQ-derivatised carbon nanomaterial-coated GC electrodes was performed.

  • electrochemical properties of gold and glassy carbon electrodes electrografted with an anthraquinone Diazonium Compound using the rotating disc electrode method
    RSC Advances, 2016
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Margus Marandi, Leonard Matisen, Väino Sammelselg, Kaido Tammeveski
    Abstract:

    In this paper, gold and glassy carbon (GC) electrodes were electrochemically grafted with anthraquinone (AQ) groups derived from Fast Red AL salt via electrochemical reduction of AQ Diazonium cations. For the first time, the electrografting was performed by combining the cyclic voltammetry (CV) or potential step method with the rotating disc electrode (RDE) technique in order to prepare thick films of AQ on Au and GC electrodes. For comparison purposes, a CV or potential step method without the RDE was also used. The attachment of thick AQ films to the Au electrode surface was confirmed by X-ray photoelectron spectroscopy and atomic force microscopy. The highest surface concentration value (ΓAQ) of AQ on the Au and GC electrodes (ca. 2.1 × 10−8 and 1.8 × 10−8 mol cm−2, respectively) was obtained by employing the combination of CV and RDE methods during the electrografting procedure. The oxygen reduction reaction results revealed that the electrochemical behaviour of AQ-modified Au electrodes does not depend on the ΓAQ value similar to the GC electrodes modified with thick AQ films. However, some differences were observed when the blocking effect of thick AQ films on Au and GC electrodes towards the ferri/ferrocyanide redox probe was studied.

Marek Mooste - One of the best experts on this subject based on the ideXlab platform.

  • oxygen reduction on graphene sheets functionalised by anthraquinone Diazonium Compound during electrochemical exfoliation of graphite
    Electrochimica Acta, 2018
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Benjamin Diby Ossonon, Daniel Belanger, Kaido Tammeveski
    Abstract:

    Abstract In this paper, the oxygen reduction reaction (ORR) was studied on anthraquinone (AQ) modified and unmodified graphene sheets in aqueous solutions. AQ-grafted graphene sheets were prepared by one-pot synthesis procedure using electrochemical exfoliation of graphite and in situ spontaneous Diazonium reduction at the same time in 0.1 M H2SO4. Unmodified and AQ-grafted graphene were characterised by thermogravimetric analysis and Raman spectroscopy. Covalent attachment of AQ on graphene was ascertained. The ORR was studied in acidic and alkaline electrolytes by the rotating disc electrode method. In both media, the prepared graphene materials were more active towards the ORR than bare glassy carbon. In alkaline solution, the number of electrons transferred per O2 molecule for AQ-modified and unmodified graphene coated glassy carbon electrodes was higher than two indicating that the formed hydrogen peroxide is partially further reduced. In addition, stability testing of the prepared electrodes during potential cycling yielded a small loss of activity.

  • oxygen reduction on anthraquinone Diazonium Compound derivatised multi walled carbon nanotube and graphene based electrodes
    Electroanalysis, 2017
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Leonard Matisen, Kaido Tammeveski
    Abstract:

    In this work, graphene and multi-walled carbon nanotubes were derivatised with anthraquinone (AQ) groups using spontaneous or electrochemical grafting of Fast Red AL salt. Glassy carbon (GC) electrodes were coated with AQ-modified carbon nanomaterials to study the oxygen reduction reaction (ORR). These nanomaterials were characterised by X-ray photoelectron spectroscopy and multilayer formation of AQ on the electrografted electrodes was observed. All the modified electrodes showed enhanced electrocatalytic activity towards the ORR in alkaline media. High AQ loading on the electrodes was found and the number of electrons transferred per O2 molecule was between 2 and 4. In addition, the stability testing of AQ-derivatised carbon nanomaterial-coated GC electrodes was performed.

  • electrochemical properties of gold and glassy carbon electrodes electrografted with an anthraquinone Diazonium Compound using the rotating disc electrode method
    RSC Advances, 2016
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Margus Marandi, Leonard Matisen, Väino Sammelselg, Kaido Tammeveski
    Abstract:

    In this paper, gold and glassy carbon (GC) electrodes were electrochemically grafted with anthraquinone (AQ) groups derived from Fast Red AL salt via electrochemical reduction of AQ Diazonium cations. For the first time, the electrografting was performed by combining the cyclic voltammetry (CV) or potential step method with the rotating disc electrode (RDE) technique in order to prepare thick films of AQ on Au and GC electrodes. For comparison purposes, a CV or potential step method without the RDE was also used. The attachment of thick AQ films to the Au electrode surface was confirmed by X-ray photoelectron spectroscopy and atomic force microscopy. The highest surface concentration value (ΓAQ) of AQ on the Au and GC electrodes (ca. 2.1 × 10−8 and 1.8 × 10−8 mol cm−2, respectively) was obtained by employing the combination of CV and RDE methods during the electrografting procedure. The oxygen reduction reaction results revealed that the electrochemical behaviour of AQ-modified Au electrodes does not depend on the ΓAQ value similar to the GC electrodes modified with thick AQ films. However, some differences were observed when the blocking effect of thick AQ films on Au and GC electrodes towards the ferri/ferrocyanide redox probe was studied.

Elo Kibenapoldsepp - One of the best experts on this subject based on the ideXlab platform.

  • oxygen reduction on graphene sheets functionalised by anthraquinone Diazonium Compound during electrochemical exfoliation of graphite
    Electrochimica Acta, 2018
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Benjamin Diby Ossonon, Daniel Belanger, Kaido Tammeveski
    Abstract:

    Abstract In this paper, the oxygen reduction reaction (ORR) was studied on anthraquinone (AQ) modified and unmodified graphene sheets in aqueous solutions. AQ-grafted graphene sheets were prepared by one-pot synthesis procedure using electrochemical exfoliation of graphite and in situ spontaneous Diazonium reduction at the same time in 0.1 M H2SO4. Unmodified and AQ-grafted graphene were characterised by thermogravimetric analysis and Raman spectroscopy. Covalent attachment of AQ on graphene was ascertained. The ORR was studied in acidic and alkaline electrolytes by the rotating disc electrode method. In both media, the prepared graphene materials were more active towards the ORR than bare glassy carbon. In alkaline solution, the number of electrons transferred per O2 molecule for AQ-modified and unmodified graphene coated glassy carbon electrodes was higher than two indicating that the formed hydrogen peroxide is partially further reduced. In addition, stability testing of the prepared electrodes during potential cycling yielded a small loss of activity.

  • oxygen reduction on anthraquinone Diazonium Compound derivatised multi walled carbon nanotube and graphene based electrodes
    Electroanalysis, 2017
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Leonard Matisen, Kaido Tammeveski
    Abstract:

    In this work, graphene and multi-walled carbon nanotubes were derivatised with anthraquinone (AQ) groups using spontaneous or electrochemical grafting of Fast Red AL salt. Glassy carbon (GC) electrodes were coated with AQ-modified carbon nanomaterials to study the oxygen reduction reaction (ORR). These nanomaterials were characterised by X-ray photoelectron spectroscopy and multilayer formation of AQ on the electrografted electrodes was observed. All the modified electrodes showed enhanced electrocatalytic activity towards the ORR in alkaline media. High AQ loading on the electrodes was found and the number of electrons transferred per O2 molecule was between 2 and 4. In addition, the stability testing of AQ-derivatised carbon nanomaterial-coated GC electrodes was performed.

  • electrochemical properties of gold and glassy carbon electrodes electrografted with an anthraquinone Diazonium Compound using the rotating disc electrode method
    RSC Advances, 2016
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Margus Marandi, Leonard Matisen, Väino Sammelselg, Kaido Tammeveski
    Abstract:

    In this paper, gold and glassy carbon (GC) electrodes were electrochemically grafted with anthraquinone (AQ) groups derived from Fast Red AL salt via electrochemical reduction of AQ Diazonium cations. For the first time, the electrografting was performed by combining the cyclic voltammetry (CV) or potential step method with the rotating disc electrode (RDE) technique in order to prepare thick films of AQ on Au and GC electrodes. For comparison purposes, a CV or potential step method without the RDE was also used. The attachment of thick AQ films to the Au electrode surface was confirmed by X-ray photoelectron spectroscopy and atomic force microscopy. The highest surface concentration value (ΓAQ) of AQ on the Au and GC electrodes (ca. 2.1 × 10−8 and 1.8 × 10−8 mol cm−2, respectively) was obtained by employing the combination of CV and RDE methods during the electrografting procedure. The oxygen reduction reaction results revealed that the electrochemical behaviour of AQ-modified Au electrodes does not depend on the ΓAQ value similar to the GC electrodes modified with thick AQ films. However, some differences were observed when the blocking effect of thick AQ films on Au and GC electrodes towards the ferri/ferrocyanide redox probe was studied.

Leonard Matisen - One of the best experts on this subject based on the ideXlab platform.

  • oxygen reduction on anthraquinone Diazonium Compound derivatised multi walled carbon nanotube and graphene based electrodes
    Electroanalysis, 2017
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Leonard Matisen, Kaido Tammeveski
    Abstract:

    In this work, graphene and multi-walled carbon nanotubes were derivatised with anthraquinone (AQ) groups using spontaneous or electrochemical grafting of Fast Red AL salt. Glassy carbon (GC) electrodes were coated with AQ-modified carbon nanomaterials to study the oxygen reduction reaction (ORR). These nanomaterials were characterised by X-ray photoelectron spectroscopy and multilayer formation of AQ on the electrografted electrodes was observed. All the modified electrodes showed enhanced electrocatalytic activity towards the ORR in alkaline media. High AQ loading on the electrodes was found and the number of electrons transferred per O2 molecule was between 2 and 4. In addition, the stability testing of AQ-derivatised carbon nanomaterial-coated GC electrodes was performed.

  • electrochemical properties of gold and glassy carbon electrodes electrografted with an anthraquinone Diazonium Compound using the rotating disc electrode method
    RSC Advances, 2016
    Co-Authors: Marek Mooste, Elo Kibenapoldsepp, Margus Marandi, Leonard Matisen, Väino Sammelselg, Kaido Tammeveski
    Abstract:

    In this paper, gold and glassy carbon (GC) electrodes were electrochemically grafted with anthraquinone (AQ) groups derived from Fast Red AL salt via electrochemical reduction of AQ Diazonium cations. For the first time, the electrografting was performed by combining the cyclic voltammetry (CV) or potential step method with the rotating disc electrode (RDE) technique in order to prepare thick films of AQ on Au and GC electrodes. For comparison purposes, a CV or potential step method without the RDE was also used. The attachment of thick AQ films to the Au electrode surface was confirmed by X-ray photoelectron spectroscopy and atomic force microscopy. The highest surface concentration value (ΓAQ) of AQ on the Au and GC electrodes (ca. 2.1 × 10−8 and 1.8 × 10−8 mol cm−2, respectively) was obtained by employing the combination of CV and RDE methods during the electrografting procedure. The oxygen reduction reaction results revealed that the electrochemical behaviour of AQ-modified Au electrodes does not depend on the ΓAQ value similar to the GC electrodes modified with thick AQ films. However, some differences were observed when the blocking effect of thick AQ films on Au and GC electrodes towards the ferri/ferrocyanide redox probe was studied.

Yuliang Yang - One of the best experts on this subject based on the ideXlab platform.

  • Single-layer graphene nanosheets with controlled grafting of polymer chains
    Journal of Materials Chemistry, 2010
    Co-Authors: Kaigang Wang, Hongbin Lu, Yuliang Yang
    Abstract:

    Single-layer graphene nanosheets (SLGNs) are prepared by reduction of well-exfoliated graphite oxide aided by a surfactant (sodium dodecylbenzene sulfonate, SDBS). Grafting density and polystyrene (PS) chain lengths are controlled by modulating the concentrations of Diazonium Compound and monomer during the grafting reaction of the initiator and the succeeding atomic transfer radical polymerization (ATRP). Atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectra and transmission electron microscopy (TEM) are used to confirm the single-layer structure of graphene sheets, covalent bonding at the interface, and distribution uniformity of grafting PS chains at the SLGN surface. Thermogravimetric analysis (TGA) is performed to assess the control of grafting density and chain length. PS chains grafted on the SLGN surface exhibited remarkably confined relaxation behavior. An increase in the glass transition temperature (Tg) of up to 18 °C is observed for high grafting density, low molecular weight polymer-grafted graphene samples. The low grafting density, high molecular weight sample shows an increase in Tg of ∼9 °C, which is attributed to superior heat conduction efficiency. The measured thermal conductivity for the PS composite film with 2.0 wt% SLGNs increase by a factor of 2.6 compared to that of the pure PS.