Kovač, Janez

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  • Kovač, Janez (7)

Author's Bibliography

Self-limiting interactions in 2D–0D system: A case study of graphene oxide and 12-tungstophosphoric acid nanocomposite

Jovanović, Zoran; Mravik, Željko; Bajuk Bogdanović, Danica; Jovanović, Sonja; Marković, Smilja; Vujković, Milica; Kovač, Janez; Vengust, Damjan; Uskoković-Marković, Snežana; Holclajtner Antunović, Ivanka

(2020)

TY  - JOUR
AU  - Jovanović, Zoran
AU  - Mravik, Željko
AU  - Bajuk Bogdanović, Danica
AU  - Jovanović, Sonja
AU  - Marković, Smilja
AU  - Vujković, Milica
AU  - Kovač, Janez
AU  - Vengust, Damjan
AU  - Uskoković-Marković, Snežana
AU  - Holclajtner Antunović, Ivanka
PY  - 2020
UR  - http://dais.sanu.ac.rs/123456789/6882
AB  - In the present study we investigated the interaction between 12-tungstophosphoric acid (WPA) and graphene oxide (GO) in their nanocomposite by utilizing the loading of WPA as an intrinsic parameter for interaction tuning. The Fourier-transform infrared spectroscopy, temperature-programmed desorption, X-ray photoelectron spectroscopy, zeta-potential measurements, thermogravimetric analysis, X-ray diffraction, Raman spectroscopy and transmission electron microscopy methods revealed that ∼5–13 wt% of WPA represents critical loading that separates two distinct contributions to GO-WPA interaction. This was explained by the self-limiting nature of GO-WPA interaction, initially controlled by high dispersion of WPA on GO (up to 13 wt%), that is eventually overpowered by WPA-WPA interaction as loading increases. As a result, the WPA agglomerates are being formed because of which the hybrid character of the nanocomposite diminishes, i.e., the properties of independent components start to be manifested to greater extent. The obtained results provide an important framework for considering possible outcomes in other 2D-0D systems, whose interaction is relevant both from fundamental and applicative point of view. Thus, the GO/WPA nanocomposite illustrates how the interactions between the components can be used for tuning the properties of nanocomposite as a whole.
T2  - Carbon
T1  - Self-limiting interactions in 2D–0D system: A case study of graphene oxide and 12-tungstophosphoric acid nanocomposite
SP  - 166
EP  - 178
VL  - 156
DO  - 10.1016/j.carbon.2019.09.072
ER  - 
@article{
author = "Jovanović, Zoran and Mravik, Željko and Bajuk Bogdanović, Danica and Jovanović, Sonja and Marković, Smilja and Vujković, Milica and Kovač, Janez and Vengust, Damjan and Uskoković-Marković, Snežana and Holclajtner Antunović, Ivanka",
year = "2020",
url = "http://dais.sanu.ac.rs/123456789/6882",
abstract = "In the present study we investigated the interaction between 12-tungstophosphoric acid (WPA) and graphene oxide (GO) in their nanocomposite by utilizing the loading of WPA as an intrinsic parameter for interaction tuning. The Fourier-transform infrared spectroscopy, temperature-programmed desorption, X-ray photoelectron spectroscopy, zeta-potential measurements, thermogravimetric analysis, X-ray diffraction, Raman spectroscopy and transmission electron microscopy methods revealed that ∼5–13 wt% of WPA represents critical loading that separates two distinct contributions to GO-WPA interaction. This was explained by the self-limiting nature of GO-WPA interaction, initially controlled by high dispersion of WPA on GO (up to 13 wt%), that is eventually overpowered by WPA-WPA interaction as loading increases. As a result, the WPA agglomerates are being formed because of which the hybrid character of the nanocomposite diminishes, i.e., the properties of independent components start to be manifested to greater extent. The obtained results provide an important framework for considering possible outcomes in other 2D-0D systems, whose interaction is relevant both from fundamental and applicative point of view. Thus, the GO/WPA nanocomposite illustrates how the interactions between the components can be used for tuning the properties of nanocomposite as a whole.",
journal = "Carbon",
title = "Self-limiting interactions in 2D–0D system: A case study of graphene oxide and 12-tungstophosphoric acid nanocomposite",
pages = "166-178",
volume = "156",
doi = "10.1016/j.carbon.2019.09.072"
}
Jovanović, Z., Mravik, Ž., Bajuk Bogdanović, D., Jovanović, S., Marković, S., Vujković, M., Kovač, J., Vengust, D., Uskoković-Marković, S.,& Holclajtner Antunović, I. (2020). Self-limiting interactions in 2D–0D system: A case study of graphene oxide and 12-tungstophosphoric acid nanocomposite.
Carbon, 156, 166-178.
https://doi.org/10.1016/j.carbon.2019.09.072
Jovanović Z, Mravik Ž, Bajuk Bogdanović D, Jovanović S, Marković S, Vujković M, Kovač J, Vengust D, Uskoković-Marković S, Holclajtner Antunović I. Self-limiting interactions in 2D–0D system: A case study of graphene oxide and 12-tungstophosphoric acid nanocomposite. Carbon. 2020;156:166-178
Jovanović Zoran, Mravik Željko, Bajuk Bogdanović Danica, Jovanović Sonja, Marković Smilja, Vujković Milica, Kovač Janez, Vengust Damjan, Uskoković-Marković Snežana, Holclajtner Antunović Ivanka, "Self-limiting interactions in 2D–0D system: A case study of graphene oxide and 12-tungstophosphoric acid nanocomposite" Carbon, 156 (2020):166-178,
https://doi.org/10.1016/j.carbon.2019.09.072 .
4
3

Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration

Marković, Smilja; Rajić, Vladimir; Veselinović, Ljiljana; Stojković Simatović, Ivana; Belošević Čavor, Jelena; Škapin, Srečo Davor; Kovač, Janez; Nikolić, Marko G.; Uskoković, Dragan

(Budapest : [s. n.], 2019)

TY  - CONF
AU  - Marković, Smilja
AU  - Rajić, Vladimir
AU  - Veselinović, Ljiljana
AU  - Stojković Simatović, Ivana
AU  - Belošević Čavor, Jelena
AU  - Škapin, Srečo Davor
AU  - Kovač, Janez
AU  - Nikolić, Marko G.
AU  - Uskoković, Dragan
PY  - 2019
UR  - http://dais.sanu.ac.rs/123456789/6997
AB  - During the last decade zinc oxide (ZnO) has attracted considerable attention as a promising material for electronic, optoelectronic and spintronic devices. ZnO has a wide bandgap (3.37 eV at room temperature) and relatively large exciton binding energy (60 meV) which enables multifunctional application. Until now ZnO-based materials have been used as UV and blue light emitters, varistors, thermistors, semiconductors, photoanodes, and other. Various approaches have been applied to improve functional properties of zinc oxide, such as: fabrication of ZnO-based heterojunction particles, particles’ surface sensitization, hydrogenation, etc. It has been found that intrinsic defects (vacancies, interstitials and antisites) in the crystal structure of a ZnO strongly influenced its electrical and optical properties. Thus, correlation of the intrinsic defects concentration with optical and electrical properties of ZnO materials is of great importance for their further application in opto-electronic devices. In this study we investigated the influence of intrinsic defects concentration on the optical, electrical and photoelectrocatalytic properties of ZnO materials. To obtain ZnO powder with a high concentration of intrinsic defects microwave processing of precipitate was employed, while for further varying of defects concentration, the powder was thermally treated in three different atmospheres: air, argon and oxygen. The ZnO powder was uniaxially pressed (P = 100 MPa) in cylindrical compacts (R= 6 mm and h approx. 3 mm) which were sintered in different atmospheres by heating rate of 10 °/min up to 1100 °C, and with dwell time of 1 h. To study a crystal structure of ZnO samples XRD and Raman spectroscopy were used, while for microstructural investigation field emission scanning electron micrographs were recorded. Optical properties were studied using UV–Vis diffuse reflectance spectroscopy. To reveal the role of intrinsic defects in ZnO crystal lattice on functional properties, XPS, photoluminescence, electroluminescence and electrochemical impedance spectra were analyzed. A detailed analysis of the experimental results imply that a high concentration of intrinsic defects, in particular oxygen vacancies, is of the greatest importance for tunable light-emitting diode application and significant for the photoanode properties. To support our experimental observation we performed ab initio calculations based on density functional theory (DFT).
PB  - Budapest : [s. n.]
C3  - Abstracts / International Workshop on Woman in Ceramic Science (WoCeram2019), April 7-9, 2019/ Budapest, Hungary, Novotel Danube Budapest
T1  - Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration
SP  - 11
EP  - 11
ER  - 
@conference{
author = "Marković, Smilja and Rajić, Vladimir and Veselinović, Ljiljana and Stojković Simatović, Ivana and Belošević Čavor, Jelena and Škapin, Srečo Davor and Kovač, Janez and Nikolić, Marko G. and Uskoković, Dragan",
year = "2019",
url = "http://dais.sanu.ac.rs/123456789/6997",
abstract = "During the last decade zinc oxide (ZnO) has attracted considerable attention as a promising material for electronic, optoelectronic and spintronic devices. ZnO has a wide bandgap (3.37 eV at room temperature) and relatively large exciton binding energy (60 meV) which enables multifunctional application. Until now ZnO-based materials have been used as UV and blue light emitters, varistors, thermistors, semiconductors, photoanodes, and other. Various approaches have been applied to improve functional properties of zinc oxide, such as: fabrication of ZnO-based heterojunction particles, particles’ surface sensitization, hydrogenation, etc. It has been found that intrinsic defects (vacancies, interstitials and antisites) in the crystal structure of a ZnO strongly influenced its electrical and optical properties. Thus, correlation of the intrinsic defects concentration with optical and electrical properties of ZnO materials is of great importance for their further application in opto-electronic devices. In this study we investigated the influence of intrinsic defects concentration on the optical, electrical and photoelectrocatalytic properties of ZnO materials. To obtain ZnO powder with a high concentration of intrinsic defects microwave processing of precipitate was employed, while for further varying of defects concentration, the powder was thermally treated in three different atmospheres: air, argon and oxygen. The ZnO powder was uniaxially pressed (P = 100 MPa) in cylindrical compacts (R= 6 mm and h approx. 3 mm) which were sintered in different atmospheres by heating rate of 10 °/min up to 1100 °C, and with dwell time of 1 h. To study a crystal structure of ZnO samples XRD and Raman spectroscopy were used, while for microstructural investigation field emission scanning electron micrographs were recorded. Optical properties were studied using UV–Vis diffuse reflectance spectroscopy. To reveal the role of intrinsic defects in ZnO crystal lattice on functional properties, XPS, photoluminescence, electroluminescence and electrochemical impedance spectra were analyzed. A detailed analysis of the experimental results imply that a high concentration of intrinsic defects, in particular oxygen vacancies, is of the greatest importance for tunable light-emitting diode application and significant for the photoanode properties. To support our experimental observation we performed ab initio calculations based on density functional theory (DFT).",
publisher = "Budapest : [s. n.]",
journal = "Abstracts / International Workshop on Woman in Ceramic Science (WoCeram2019), April 7-9, 2019/ Budapest, Hungary, Novotel Danube Budapest",
title = "Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration",
pages = "11-11"
}
Marković, S., Rajić, V., Veselinović, L., Stojković Simatović, I., Belošević Čavor, J., Škapin, S. D., Kovač, J., Nikolić, M. G.,& Uskoković, D. (2019). Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration.
Abstracts / International Workshop on Woman in Ceramic Science (WoCeram2019), April 7-9, 2019/ Budapest, Hungary, Novotel Danube Budapest
Budapest : [s. n.]., 11-11.
Marković S, Rajić V, Veselinović L, Stojković Simatović I, Belošević Čavor J, Škapin SD, Kovač J, Nikolić MG, Uskoković D. Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration. Abstracts / International Workshop on Woman in Ceramic Science (WoCeram2019), April 7-9, 2019/ Budapest, Hungary, Novotel Danube Budapest. 2019;:11-11
Marković Smilja, Rajić Vladimir, Veselinović Ljiljana, Stojković Simatović Ivana, Belošević Čavor Jelena, Škapin Srečo Davor, Kovač Janez, Nikolić Marko G., Uskoković Dragan, "Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration" Abstracts / International Workshop on Woman in Ceramic Science (WoCeram2019), April 7-9, 2019/ Budapest, Hungary, Novotel Danube Budapest (2019):11-11

Study of the interaction between graphene oxide and 12-tungstophosphoric acid in their nanocomposite

Mravik, Željko; Bajuk Bogdanović, Danica; Marković, Smilja; Kovač, Janez; Holclajtner Antunović, Ivanka; Jovanović, Zoran

(Belgrade : Materials Research Society of Serbia, 2018)

TY  - CONF
AU  - Mravik, Željko
AU  - Bajuk Bogdanović, Danica
AU  - Marković, Smilja
AU  - Kovač, Janez
AU  - Holclajtner Antunović, Ivanka
AU  - Jovanović, Zoran
PY  - 2018
UR  - http://dais.sanu.ac.rs/123456789/3666
AB  - The rich surface chemistry and large surface area of graphene oxide (GO) provide a platform for various functional materials that synergistically enhance charge storage properties of the composite. In present work we have investigated interaction between GO and 12- thungstophosphoric acid (WPA) in their nanocomposites as a function of different mass ratio of constituents. For this purpose, the Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS), temperature programmed desorption method (TPD) and thermogravimetric/differential thermal analysis (TGA-DTA) methods were used. FTIR spectra have shown shifts and splitting of characteristic bands of WPA as a result of interactions with GO. Both XPS and TPD methods have shown an initial decrease of the total amount of surface oxygen groups of GO, with a minimum at around 10 wt.% of WPA, above which a restoration of the amount of surface oxygen groups was noticed. TGA-DTA analysis revealed an improved thermal stability of the material up to 25 wt.% of WPA; at higher loading of WPA the thermal properties of nanocomposite became alike to the ones of individual components. The obtained results suggest optimal conditions for preparation of GO-WPA nanocomposites for electrochemical charge storage applications.
PB  - Belgrade : Materials Research Society of Serbia
C3  - Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018
T1  - Study of the interaction between graphene oxide and 12-tungstophosphoric acid in their nanocomposite
SP  - 110
EP  - 110
ER  - 
@conference{
author = "Mravik, Željko and Bajuk Bogdanović, Danica and Marković, Smilja and Kovač, Janez and Holclajtner Antunović, Ivanka and Jovanović, Zoran",
year = "2018",
url = "http://dais.sanu.ac.rs/123456789/3666",
abstract = "The rich surface chemistry and large surface area of graphene oxide (GO) provide a platform for various functional materials that synergistically enhance charge storage properties of the composite. In present work we have investigated interaction between GO and 12- thungstophosphoric acid (WPA) in their nanocomposites as a function of different mass ratio of constituents. For this purpose, the Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS), temperature programmed desorption method (TPD) and thermogravimetric/differential thermal analysis (TGA-DTA) methods were used. FTIR spectra have shown shifts and splitting of characteristic bands of WPA as a result of interactions with GO. Both XPS and TPD methods have shown an initial decrease of the total amount of surface oxygen groups of GO, with a minimum at around 10 wt.% of WPA, above which a restoration of the amount of surface oxygen groups was noticed. TGA-DTA analysis revealed an improved thermal stability of the material up to 25 wt.% of WPA; at higher loading of WPA the thermal properties of nanocomposite became alike to the ones of individual components. The obtained results suggest optimal conditions for preparation of GO-WPA nanocomposites for electrochemical charge storage applications.",
publisher = "Belgrade : Materials Research Society of Serbia",
journal = "Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018",
title = "Study of the interaction between graphene oxide and 12-tungstophosphoric acid in their nanocomposite",
pages = "110-110"
}
Mravik, Ž., Bajuk Bogdanović, D., Marković, S., Kovač, J., Holclajtner Antunović, I.,& Jovanović, Z. (2018). Study of the interaction between graphene oxide and 12-tungstophosphoric acid in their nanocomposite.
Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018
Belgrade : Materials Research Society of Serbia., 110-110.
Mravik Ž, Bajuk Bogdanović D, Marković S, Kovač J, Holclajtner Antunović I, Jovanović Z. Study of the interaction between graphene oxide and 12-tungstophosphoric acid in their nanocomposite. Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018. 2018;:110-110
Mravik Željko, Bajuk Bogdanović Danica, Marković Smilja, Kovač Janez, Holclajtner Antunović Ivanka, Jovanović Zoran, "Study of the interaction between graphene oxide and 12-tungstophosphoric acid in their nanocomposite" Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018 (2018):110-110

Ni-(Ebonex-supported Ir) composite coatings as electrocatalysts for alkaline water electrolysis. Part II: Oxygen evolution

Jović, Borka; Lačnjevac, Uroš; Jović, Vladimir; Gajić Krstajić, Ljiljana; Kovač, Janez; Poleti, Dejan; Krstajić, Nedeljko

(2016)

TY  - JOUR
AU  - Jović, Borka
AU  - Lačnjevac, Uroš
AU  - Jović, Vladimir
AU  - Gajić Krstajić, Ljiljana
AU  - Kovač, Janez
AU  - Poleti, Dejan
AU  - Krstajić, Nedeljko
PY  - 2016
UR  - http://dais.sanu.ac.rs/123456789/15978
AB  - The oxygen evolution reaction (OER) was studied at pure Ni and Ni-(Ebonex/Ir) composite coatings in 1 M NaOH solution at 25 °C. Ni-(Ebonex-supported Ir) coatings were electrodeposited from a nickel Watts bath containing different concentrations of suspended Ebonex/Ir particles (0–2 g dm−3) onto a Ni 40 mesh substrate. The surface morphology of the coatings was examined by scanning electron microscopy (SEM), the surface composition by energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRPD) and X-ray photoelectron spectroscopy (XPS), whereas the electrochemical properties were studied by electrochemical impedance spectroscopy (EIS), polarization measurements and cyclic voltammetry (CV). It was shown that the roughness factor of Ni-(Ebonex/Ir) composite coatings calculated relative to the surface area of the pure Ni sample increased with the increasing content of Ebonex/Ir particles in the bath to a maximum value of 40.6. All samples displayed a Tafel slope of about 60 mV dec−1 in the potential range corresponding to lower current densities for the OER. The increase of the apparent activity for the OER at Ni-(Ebonex/Ir) coatings compared with the pure Ni coating was attributed only to the increase of the electrochemically active surface area. Although the pure Ni coating initially exhibited higher intrinsic catalytic activity for the OER than the composite coatings, it also showed a drastic loss of activity after subjecting to continuous oxygen evolution at j = 50 mA cm−2 for 24 h (ΔE = 395 mV). At the same time, the OER overpotential at Ni-(Ebonex/Ir) coatings only negligibly increased after the stability test (ΔE = 22 mV). The improved retention of catalytic activity observed with Ni-(Ebonex/Ir) coatings was ascribed to the presence of IrO2, which inhibited the formation of the inactive γ-NiOOH phase.
T2  - International Journal of Hydrogen Energy
T1  - Ni-(Ebonex-supported Ir) composite coatings as electrocatalysts for alkaline water electrolysis. Part II: Oxygen evolution
SP  - 20502
EP  - 20514
VL  - 41
IS  - 45
DO  - 10.1016/j.ijhydene.2016.08.226
ER  - 
@article{
author = "Jović, Borka and Lačnjevac, Uroš and Jović, Vladimir and Gajić Krstajić, Ljiljana and Kovač, Janez and Poleti, Dejan and Krstajić, Nedeljko",
year = "2016",
url = "http://dais.sanu.ac.rs/123456789/15978",
abstract = "The oxygen evolution reaction (OER) was studied at pure Ni and Ni-(Ebonex/Ir) composite coatings in 1 M NaOH solution at 25 °C. Ni-(Ebonex-supported Ir) coatings were electrodeposited from a nickel Watts bath containing different concentrations of suspended Ebonex/Ir particles (0–2 g dm−3) onto a Ni 40 mesh substrate. The surface morphology of the coatings was examined by scanning electron microscopy (SEM), the surface composition by energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRPD) and X-ray photoelectron spectroscopy (XPS), whereas the electrochemical properties were studied by electrochemical impedance spectroscopy (EIS), polarization measurements and cyclic voltammetry (CV). It was shown that the roughness factor of Ni-(Ebonex/Ir) composite coatings calculated relative to the surface area of the pure Ni sample increased with the increasing content of Ebonex/Ir particles in the bath to a maximum value of 40.6. All samples displayed a Tafel slope of about 60 mV dec−1 in the potential range corresponding to lower current densities for the OER. The increase of the apparent activity for the OER at Ni-(Ebonex/Ir) coatings compared with the pure Ni coating was attributed only to the increase of the electrochemically active surface area. Although the pure Ni coating initially exhibited higher intrinsic catalytic activity for the OER than the composite coatings, it also showed a drastic loss of activity after subjecting to continuous oxygen evolution at j = 50 mA cm−2 for 24 h (ΔE = 395 mV). At the same time, the OER overpotential at Ni-(Ebonex/Ir) coatings only negligibly increased after the stability test (ΔE = 22 mV). The improved retention of catalytic activity observed with Ni-(Ebonex/Ir) coatings was ascribed to the presence of IrO2, which inhibited the formation of the inactive γ-NiOOH phase.",
journal = "International Journal of Hydrogen Energy",
title = "Ni-(Ebonex-supported Ir) composite coatings as electrocatalysts for alkaline water electrolysis. Part II: Oxygen evolution",
pages = "20502-20514",
volume = "41",
number = "45",
doi = "10.1016/j.ijhydene.2016.08.226"
}
Jović, B., Lačnjevac, U., Jović, V., Gajić Krstajić, L., Kovač, J., Poleti, D.,& Krstajić, N. (2016). Ni-(Ebonex-supported Ir) composite coatings as electrocatalysts for alkaline water electrolysis. Part II: Oxygen evolution.
International Journal of Hydrogen Energy, 41(45), 20502-20514.
https://doi.org/10.1016/j.ijhydene.2016.08.226
Jović B, Lačnjevac U, Jović V, Gajić Krstajić L, Kovač J, Poleti D, Krstajić N. Ni-(Ebonex-supported Ir) composite coatings as electrocatalysts for alkaline water electrolysis. Part II: Oxygen evolution. International Journal of Hydrogen Energy. 2016;41(45):20502-20514
Jović Borka, Lačnjevac Uroš, Jović Vladimir, Gajić Krstajić Ljiljana, Kovač Janez, Poleti Dejan, Krstajić Nedeljko, "Ni-(Ebonex-supported Ir) composite coatings as electrocatalysts for alkaline water electrolysis. Part II: Oxygen evolution" International Journal of Hydrogen Energy, 41, no. 45 (2016):20502-20514,
https://doi.org/10.1016/j.ijhydene.2016.08.226 .
17
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Pt nanoparticles on tin oxide based support as a beneficial catalyst for oxygen reduction in alkaline solutions

Elezović, Nevenka; Radmilović, Velimir R.; Kovač, Janez; Babić, Biljana M.; Gajić Krstajić, Ljiljana; Krstajić, Nedeljko

(2015)

TY  - JOUR
AU  - Elezović, Nevenka
AU  - Radmilović, Velimir R.
AU  - Kovač, Janez
AU  - Babić, Biljana M.
AU  - Gajić Krstajić, Ljiljana
AU  - Krstajić, Nedeljko
PY  - 2015
UR  - http://dais.sanu.ac.rs/123456789/3354
AB  - A platinum nanocatalyst on Sb doped tin oxide support (Sb-SnO2) was synthesized and characterized as a catalyst for oxygen reduction reaction in 0.1 mol dm(-3) NaOH solution at 25 degrees C. Sb (5%) doped tin oxide support was synthesized by a modified hydrazine reduction procedure. The platinum nanocatalyst (20% Pt) on Sb-SnO2 support was synthesized by a borohydride reduction method. The synthesized support and catalyst were characterized by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) and X-ray diffraction technique (XRD). X-ray photoelectron spectroscopy was applied to characterize the chemical status of elements before and after Pt-treatment. XPS spectra of Sn 3d, Pt 4f, Sb 3d and O 1s revealed that the Pt-deposition on Sb-SnO2 support induced the reduction of the Sn(4+) oxidation state to Sn(2+) and Sn(0) states, while Pt remained in the metallic state and Sb was in the (3+) oxidation state. Homogenous Pt nanoparticle distribution over the support, without pronounced particle agglomeration, was confirmed by HRTEM technique. The average Pt particle size was 2.9 nm. The electrochemically active Pt surface area of the catalyst was determined by the integration of the cyclic voltammetry curve in the potential region of underpotential deposition of hydrogen, after double layer charge correction, taking into account the reference value of 210 mu C cm(-2) for full monolayer coverage. This calculation gave the value of 51 m(2) g(-1). The kinetics of the oxygen reduction reaction with Pt/[Sb-SnO2 catalyst was studied by cyclic voltammetry and linear sweep voltammetry using a rotating gold disc electrode. Two different Tafel slopes were observed: one close to 60 mV dec(-1) in the low current density region, and another at similar to 120 mV dec(-1) in the higher current densities region, as was already referred in previous reports for the oxygen reduction reaction with polycrystalline Pt, as well as with different Pt based nanocatalysts. The specific activities for oxygen reduction, expressed in terms of kinetic current densities per electrochemically Pt active surface area, as well as per mass of Pt loaded, at the constant potential of practical interest (0.85 V and 0.90 V vs. RHE), were compared to a carbon supported (Vulcan XC-72) catalyst. The Pt/[Sb-SnO2 catalyst exhibited similar catalytic activity for oxygen reduction reaction like carbon supported one. The advantages of the carbon free support application in terms of the durability and stability of the catalysts were proved by accelerated stability tests.
T2  - RSC Advances
T1  - Pt nanoparticles on tin oxide based support as a beneficial catalyst for oxygen reduction in alkaline solutions
SP  - 15923
EP  - 15929
VL  - 5
IS  - 21
DO  - 10.1039/c4ra13391a
ER  - 
@article{
author = "Elezović, Nevenka and Radmilović, Velimir R. and Kovač, Janez and Babić, Biljana M. and Gajić Krstajić, Ljiljana and Krstajić, Nedeljko",
year = "2015",
url = "http://dais.sanu.ac.rs/123456789/3354",
abstract = "A platinum nanocatalyst on Sb doped tin oxide support (Sb-SnO2) was synthesized and characterized as a catalyst for oxygen reduction reaction in 0.1 mol dm(-3) NaOH solution at 25 degrees C. Sb (5%) doped tin oxide support was synthesized by a modified hydrazine reduction procedure. The platinum nanocatalyst (20% Pt) on Sb-SnO2 support was synthesized by a borohydride reduction method. The synthesized support and catalyst were characterized by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) and X-ray diffraction technique (XRD). X-ray photoelectron spectroscopy was applied to characterize the chemical status of elements before and after Pt-treatment. XPS spectra of Sn 3d, Pt 4f, Sb 3d and O 1s revealed that the Pt-deposition on Sb-SnO2 support induced the reduction of the Sn(4+) oxidation state to Sn(2+) and Sn(0) states, while Pt remained in the metallic state and Sb was in the (3+) oxidation state. Homogenous Pt nanoparticle distribution over the support, without pronounced particle agglomeration, was confirmed by HRTEM technique. The average Pt particle size was 2.9 nm. The electrochemically active Pt surface area of the catalyst was determined by the integration of the cyclic voltammetry curve in the potential region of underpotential deposition of hydrogen, after double layer charge correction, taking into account the reference value of 210 mu C cm(-2) for full monolayer coverage. This calculation gave the value of 51 m(2) g(-1). The kinetics of the oxygen reduction reaction with Pt/[Sb-SnO2 catalyst was studied by cyclic voltammetry and linear sweep voltammetry using a rotating gold disc electrode. Two different Tafel slopes were observed: one close to 60 mV dec(-1) in the low current density region, and another at similar to 120 mV dec(-1) in the higher current densities region, as was already referred in previous reports for the oxygen reduction reaction with polycrystalline Pt, as well as with different Pt based nanocatalysts. The specific activities for oxygen reduction, expressed in terms of kinetic current densities per electrochemically Pt active surface area, as well as per mass of Pt loaded, at the constant potential of practical interest (0.85 V and 0.90 V vs. RHE), were compared to a carbon supported (Vulcan XC-72) catalyst. The Pt/[Sb-SnO2 catalyst exhibited similar catalytic activity for oxygen reduction reaction like carbon supported one. The advantages of the carbon free support application in terms of the durability and stability of the catalysts were proved by accelerated stability tests.",
journal = "RSC Advances",
title = "Pt nanoparticles on tin oxide based support as a beneficial catalyst for oxygen reduction in alkaline solutions",
pages = "15923-15929",
volume = "5",
number = "21",
doi = "10.1039/c4ra13391a"
}
Elezović, N., Radmilović, V. R., Kovač, J., Babić, B. M., Gajić Krstajić, L.,& Krstajić, N. (2015). Pt nanoparticles on tin oxide based support as a beneficial catalyst for oxygen reduction in alkaline solutions.
RSC Advances, 5(21), 15923-15929.
https://doi.org/10.1039/c4ra13391a
Elezović N, Radmilović VR, Kovač J, Babić BM, Gajić Krstajić L, Krstajić N. Pt nanoparticles on tin oxide based support as a beneficial catalyst for oxygen reduction in alkaline solutions. RSC Advances. 2015;5(21):15923-15929
Elezović Nevenka, Radmilović Velimir R., Kovač Janez, Babić Biljana M., Gajić Krstajić Ljiljana, Krstajić Nedeljko, "Pt nanoparticles on tin oxide based support as a beneficial catalyst for oxygen reduction in alkaline solutions" RSC Advances, 5, no. 21 (2015):15923-15929,
https://doi.org/10.1039/c4ra13391a .
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21

Electrochemical oxygen reduction at platinum catalyst on tin oxide based support in alkaline solution

Gajić Krstajić, Ljiljana; Elezović, Nevenka; Babić, Biljana M.; Kovač, Janez; Radmilović, Velimir R.; Krstajić, Nedeljko

(Belgrade : Materials Research Society of Serbia, 2014)

TY  - CONF
AU  - Gajić Krstajić, Ljiljana
AU  - Elezović, Nevenka
AU  - Babić, Biljana M.
AU  - Kovač, Janez
AU  - Radmilović, Velimir R.
AU  - Krstajić, Nedeljko
PY  - 2014
UR  - http://dais.sanu.ac.rs/123456789/560
AB  - Platinum on Sb doped tin oxide support (Sb/SnO2) was synthesized and characterized as the catalyst for oxygen reduction reaction in 0.1 mol dm-3NaOH solution, at 25oC. Sb (5%) doped tin oxide support was synthesized by sol-gel procedure. Platinum nanocatalyst (20% Pt) on Sb-SnO2 support was synthesized by borohydride reduction method. Synthesized support and catalyst were characterized by BET (Brunauer, Emmett, Teller), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). XRD diffraction spectra of the support contained only SnO2 belonging peaks. X-ray photoelectron spectroscopy was applied to characterize chemical status of elements before and after Pt-treatment. XPS spectra Sn 3d, Pt 4f, Sb 3d and O 1s revealed that the Pt-deposition on Sb+SnO2 support induced reduction of Sn(4+) oxidation state to Sn(2+) and Sn(0) states, while Pt remained in metallic state and Sb was in (3+) oxidation state. Homogenous Pt nanoparticles distribution over the support, without pronounced particle agglomeration was confirmed by HRTEM technique. The average Pt particle size was 2.9 nm. Electrochemically active Pt surface area of the catalyst was determined by integration of the cyclic voltammetry curve in the potential region of underpotential deposition of hydrogen, after double layer charge correction, taking into account the reference value of 210 μC cm-2 for full monolayer coverage. This calculation gave the value of 51 m2 g-1. Kinetics of the oxygen reduction reaction at Pt/Sb-SnO2 catalyst was studied by cyclic voltammetry and linear sweep voltammetry at rotating gold disc electrode. Two different Tafel slope were observed: one close to 60 mV dec-1 in low current density region, and other ~120 mV dec-1 in higher current densities region, as it was already referred in literature for oxygen reduction reaction at polycrystalline Pt, as well as at different Pt based nanocatalysts. The specific activities for oxygen reduction, expressed in terms of kinetic current densities per electrochemically Pt active surface area, as well as per mass of Pt loaded, at the constant potential of practical interest (0.85 V and 0.90 V vs RHE), were compared to carbon supported (Vulcan XC-72) catalyst. Pt/Sb-SnO2 catalyst exhibited similar catalytic activity for oxygen reduction reaction like carbon supported one. The advantages of carbon free support application in terms of durability and stability of the catalysts were discussed.
PB  - Belgrade : Materials Research Society of Serbia
C3  - The Sixteenth Annual Conference YUCOMAT 2014: Programme and the Book of Abstracts
T1  - Electrochemical oxygen reduction at platinum catalyst on tin oxide based support in alkaline solution
SP  - 90
EP  - 90
ER  - 
@conference{
author = "Gajić Krstajić, Ljiljana and Elezović, Nevenka and Babić, Biljana M. and Kovač, Janez and Radmilović, Velimir R. and Krstajić, Nedeljko",
year = "2014",
url = "http://dais.sanu.ac.rs/123456789/560",
abstract = "Platinum on Sb doped tin oxide support (Sb/SnO2) was synthesized and characterized as the catalyst for oxygen reduction reaction in 0.1 mol dm-3NaOH solution, at 25oC. Sb (5%) doped tin oxide support was synthesized by sol-gel procedure. Platinum nanocatalyst (20% Pt) on Sb-SnO2 support was synthesized by borohydride reduction method. Synthesized support and catalyst were characterized by BET (Brunauer, Emmett, Teller), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). XRD diffraction spectra of the support contained only SnO2 belonging peaks. X-ray photoelectron spectroscopy was applied to characterize chemical status of elements before and after Pt-treatment. XPS spectra Sn 3d, Pt 4f, Sb 3d and O 1s revealed that the Pt-deposition on Sb+SnO2 support induced reduction of Sn(4+) oxidation state to Sn(2+) and Sn(0) states, while Pt remained in metallic state and Sb was in (3+) oxidation state. Homogenous Pt nanoparticles distribution over the support, without pronounced particle agglomeration was confirmed by HRTEM technique. The average Pt particle size was 2.9 nm. Electrochemically active Pt surface area of the catalyst was determined by integration of the cyclic voltammetry curve in the potential region of underpotential deposition of hydrogen, after double layer charge correction, taking into account the reference value of 210 μC cm-2 for full monolayer coverage. This calculation gave the value of 51 m2 g-1. Kinetics of the oxygen reduction reaction at Pt/Sb-SnO2 catalyst was studied by cyclic voltammetry and linear sweep voltammetry at rotating gold disc electrode. Two different Tafel slope were observed: one close to 60 mV dec-1 in low current density region, and other ~120 mV dec-1 in higher current densities region, as it was already referred in literature for oxygen reduction reaction at polycrystalline Pt, as well as at different Pt based nanocatalysts. The specific activities for oxygen reduction, expressed in terms of kinetic current densities per electrochemically Pt active surface area, as well as per mass of Pt loaded, at the constant potential of practical interest (0.85 V and 0.90 V vs RHE), were compared to carbon supported (Vulcan XC-72) catalyst. Pt/Sb-SnO2 catalyst exhibited similar catalytic activity for oxygen reduction reaction like carbon supported one. The advantages of carbon free support application in terms of durability and stability of the catalysts were discussed.",
publisher = "Belgrade : Materials Research Society of Serbia",
journal = "The Sixteenth Annual Conference YUCOMAT 2014: Programme and the Book of Abstracts",
title = "Electrochemical oxygen reduction at platinum catalyst on tin oxide based support in alkaline solution",
pages = "90-90"
}
Gajić Krstajić, L., Elezović, N., Babić, B. M., Kovač, J., Radmilović, V. R.,& Krstajić, N. (2014). Electrochemical oxygen reduction at platinum catalyst on tin oxide based support in alkaline solution.
The Sixteenth Annual Conference YUCOMAT 2014: Programme and the Book of Abstracts
Belgrade : Materials Research Society of Serbia., 90-90.
Gajić Krstajić L, Elezović N, Babić BM, Kovač J, Radmilović VR, Krstajić N. Electrochemical oxygen reduction at platinum catalyst on tin oxide based support in alkaline solution. The Sixteenth Annual Conference YUCOMAT 2014: Programme and the Book of Abstracts. 2014;:90-90
Gajić Krstajić Ljiljana, Elezović Nevenka, Babić Biljana M., Kovač Janez, Radmilović Velimir R., Krstajić Nedeljko, "Electrochemical oxygen reduction at platinum catalyst on tin oxide based support in alkaline solution" The Sixteenth Annual Conference YUCOMAT 2014: Programme and the Book of Abstracts (2014):90-90

Ti substrate coated with composite Cr–MoO2 coatings as highly selective cathode materials in hypochlorite production

Lačnjevac, Uroš; Jović, Borka; Gajić Krstajić, Ljiljana; Kovač, Janez; Jović, Vladimir; Krstajić, Nedeljko

(Elsevier, 2013)

TY  - JOUR
AU  - Lačnjevac, Uroš
AU  - Jović, Borka
AU  - Gajić Krstajić, Ljiljana
AU  - Kovač, Janez
AU  - Jović, Vladimir
AU  - Krstajić, Nedeljko
PY  - 2013
UR  - http://dais.sanu.ac.rs/123456789/358
AB  - The aim of this work was to investigate the possibility of preparation of the composite Cr–MoO2 coatings onto steel and titanium substrates as cathode materials with high selective properties which imply the suppression of hypochlorite reduction as a side reaction during hypochlorite commercial production. The electrodes were prepared by simultaneous deposition of chromium and suspended MoO2 particles on titanium substrate from acid chromium (VI) bath. The current efficiency for electrodeposition of the composite coatings did not vary significantly with the concentration of suspended MoO2 particles. The content of molybdenum in the deposits was relatively low (0.2–1.5 at.%) and increased with increasing the concentration of suspended MoO2 particles in the bath, in the range from 0 to 10 g dm−3. With further increase in the concentration of MoO2, the content of molybdenum in the coating varied insignificantly.

X-ray photoelectron spectroscopy-XPS and EDS analysis were applied to analyze elemental composition and chemical bonding of elements on the surface and in the sub-surface region of obtained coatings. When the concentration of MoO2 particles in the bath was raised above 5 g dm−3, the appearance of the coating changed from the typical pure chromium deposit to needle-like deposit with the appearance of black inclusions on the surface. XPS analysis and corresponding Cr 2p spectra showed the presence of chromium oxide, probably Cr2O3 with Cr(3+) valence state on the surface and in the sub-surface region of Cr–MoO2 coatings.

Investigation of the current efficiency for the hydrogen evolution reaction (HER) on Cr–MoO2 cathodes showed that it increased with the increase of the content of MoO2 particles in the coating, exceeding the value of 97% in the solution with the hypochlorite concentration of 0.21 mol dm−3. Under the same conditions, the current efficiency for the HER on Ti and Ti/Cr cathodes is very low (≈20%), and corresponding polarization curves confirmed the fact that the side reaction of hypochlorite reduction takes place in the diffusion-controlled regime on these electrodes. The high selectivity of Cr–MoO2 coating is probably caused by the presence of chromium oxide (hydroxide) formed at the surface of the coating during co-deposition of Cr and MoO2 particles, which prevents hypochlorite reduction on the cathode during the HER.
PB  - Elsevier
T2  - Electrochimica Acta
T1  - Ti substrate coated with composite Cr–MoO2 coatings as highly selective cathode materials in hypochlorite production
SP  - 34
EP  - 42
VL  - 96
IS  - 30
DO  - 10.1016/j.electacta.2013.02.086
ER  - 
@article{
author = "Lačnjevac, Uroš and Jović, Borka and Gajić Krstajić, Ljiljana and Kovač, Janez and Jović, Vladimir and Krstajić, Nedeljko",
year = "2013",
url = "http://dais.sanu.ac.rs/123456789/358",
abstract = "The aim of this work was to investigate the possibility of preparation of the composite Cr–MoO2 coatings onto steel and titanium substrates as cathode materials with high selective properties which imply the suppression of hypochlorite reduction as a side reaction during hypochlorite commercial production. The electrodes were prepared by simultaneous deposition of chromium and suspended MoO2 particles on titanium substrate from acid chromium (VI) bath. The current efficiency for electrodeposition of the composite coatings did not vary significantly with the concentration of suspended MoO2 particles. The content of molybdenum in the deposits was relatively low (0.2–1.5 at.%) and increased with increasing the concentration of suspended MoO2 particles in the bath, in the range from 0 to 10 g dm−3. With further increase in the concentration of MoO2, the content of molybdenum in the coating varied insignificantly.

X-ray photoelectron spectroscopy-XPS and EDS analysis were applied to analyze elemental composition and chemical bonding of elements on the surface and in the sub-surface region of obtained coatings. When the concentration of MoO2 particles in the bath was raised above 5 g dm−3, the appearance of the coating changed from the typical pure chromium deposit to needle-like deposit with the appearance of black inclusions on the surface. XPS analysis and corresponding Cr 2p spectra showed the presence of chromium oxide, probably Cr2O3 with Cr(3+) valence state on the surface and in the sub-surface region of Cr–MoO2 coatings.

Investigation of the current efficiency for the hydrogen evolution reaction (HER) on Cr–MoO2 cathodes showed that it increased with the increase of the content of MoO2 particles in the coating, exceeding the value of 97% in the solution with the hypochlorite concentration of 0.21 mol dm−3. Under the same conditions, the current efficiency for the HER on Ti and Ti/Cr cathodes is very low (≈20%), and corresponding polarization curves confirmed the fact that the side reaction of hypochlorite reduction takes place in the diffusion-controlled regime on these electrodes. The high selectivity of Cr–MoO2 coating is probably caused by the presence of chromium oxide (hydroxide) formed at the surface of the coating during co-deposition of Cr and MoO2 particles, which prevents hypochlorite reduction on the cathode during the HER.",
publisher = "Elsevier",
journal = "Electrochimica Acta",
title = "Ti substrate coated with composite Cr–MoO2 coatings as highly selective cathode materials in hypochlorite production",
pages = "34-42",
volume = "96",
number = "30",
doi = "10.1016/j.electacta.2013.02.086"
}
Lačnjevac, U., Jović, B., Gajić Krstajić, L., Kovač, J., Jović, V.,& Krstajić, N. (2013). Ti substrate coated with composite Cr–MoO2 coatings as highly selective cathode materials in hypochlorite production.
Electrochimica Acta
Elsevier., 96(30), 34-42.
https://doi.org/10.1016/j.electacta.2013.02.086
Lačnjevac U, Jović B, Gajić Krstajić L, Kovač J, Jović V, Krstajić N. Ti substrate coated with composite Cr–MoO2 coatings as highly selective cathode materials in hypochlorite production. Electrochimica Acta. 2013;96(30):34-42
Lačnjevac Uroš, Jović Borka, Gajić Krstajić Ljiljana, Kovač Janez, Jović Vladimir, Krstajić Nedeljko, "Ti substrate coated with composite Cr–MoO2 coatings as highly selective cathode materials in hypochlorite production" Electrochimica Acta, 96, no. 30 (2013):34-42,
https://doi.org/10.1016/j.electacta.2013.02.086 .
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