TY  - JOUR
AU  - Krstajić Pajić, Mila N.
AU  - Dobrota, Ana S.
AU  - Mazare, Anca
AU  - Đurđić, Slađana Z.
AU  - Hwang, Imgon
AU  - Skorodumova, Natalia V.
AU  - Manojlović, Dragan D.
AU  - Vasilić, Rastko
AU  - Pašti, Igor A.
AU  - Schmuki, Patrik
AU  - Lačnjevac, Uroš
PY  - 2023
UR  - http://cherry.chem.bg.ac.rs/handle/123456789/6277
AB  - Efficient cathodes for the hydrogen evolution reaction (HER) in acidic water electrolysis rely on the use of expensive platinum group metals (PGMs). However, to achieve economically viable operation, both the content of PGMs must be reduced and their intrinsically strong H adsorption mitigated. Herein, we show that the surface effects of hydrogenated TiO2 nanotube (TNT) arrays can make osmium, a so far less-explored PGM, a highly active HER electrocatalyst. These defect-rich TiO2 nanostructures provide an interactive scaffold for the galvanic deposition of Os particles with modulated adsorption properties. Through systematic investigations, we identify the synthesis conditions (OsCl3 concentration/temperature/reaction time) that yield a progressive improvement in Os deposition rate and mass loading, thereby decreasing the HER overpotential. At the same time, the Os particles deposited by this procedure remain mainly sub-nanometric and entirely cover the inner tube walls. An optimally balanced Os@TNT composite prepared at 3 mM/55 °C/30 min exhibits a record low overpotential (η) of 61 mV at a current density of 100 mA cm–2, a high mass activity of 20.8 A mgOs–1 at 80 mV, and a stable performance in an acidic medium. Density functional theory calculations indicate the existence of strong interactions between the hydrogenated TiO2 surface and small Os clusters, which may weaken the Os–H* binding strength and thus boost the intrinsic HER activity of Os centers. The results presented in this study offer new directions for the fabrication of cost-effective PGM-based catalysts and a better understanding of the synergistic electronic interactions at the PGM|TiO2 interface.
PB  - American Chemical Society
T2  - ACS Applied Materials & Interfaces
T1  - Activation of Osmium by the Surface Effects of Hydrogenated TiO2 Nanotube Arrays for Enhanced Hydrogen Evolution Reaction Performance
VL  - 15
IS  - 26
SP  - 31459
EP  - 31469
DO  - 10.1021/acsami.3c04498
ER  - 

@article{
author = "Krstajić Pajić, Mila N. and Dobrota, Ana S. and Mazare, Anca and Đurđić, Slađana Z. and Hwang, Imgon and Skorodumova, Natalia V. and Manojlović, Dragan D. and Vasilić, Rastko and Pašti, Igor A. and Schmuki, Patrik and Lačnjevac, Uroš",
year = "2023",
abstract = "Efficient cathodes for the hydrogen evolution reaction (HER) in acidic water electrolysis rely on the use of expensive platinum group metals (PGMs). However, to achieve economically viable operation, both the content of PGMs must be reduced and their intrinsically strong H adsorption mitigated. Herein, we show that the surface effects of hydrogenated TiO2 nanotube (TNT) arrays can make osmium, a so far less-explored PGM, a highly active HER electrocatalyst. These defect-rich TiO2 nanostructures provide an interactive scaffold for the galvanic deposition of Os particles with modulated adsorption properties. Through systematic investigations, we identify the synthesis conditions (OsCl3 concentration/temperature/reaction time) that yield a progressive improvement in Os deposition rate and mass loading, thereby decreasing the HER overpotential. At the same time, the Os particles deposited by this procedure remain mainly sub-nanometric and entirely cover the inner tube walls. An optimally balanced Os@TNT composite prepared at 3 mM/55 °C/30 min exhibits a record low overpotential (η) of 61 mV at a current density of 100 mA cm–2, a high mass activity of 20.8 A mgOs–1 at 80 mV, and a stable performance in an acidic medium. Density functional theory calculations indicate the existence of strong interactions between the hydrogenated TiO2 surface and small Os clusters, which may weaken the Os–H* binding strength and thus boost the intrinsic HER activity of Os centers. The results presented in this study offer new directions for the fabrication of cost-effective PGM-based catalysts and a better understanding of the synergistic electronic interactions at the PGM|TiO2 interface.",
publisher = "American Chemical Society",
journal = "ACS Applied Materials & Interfaces",
title = "Activation of Osmium by the Surface Effects of Hydrogenated TiO2 Nanotube Arrays for Enhanced Hydrogen Evolution Reaction Performance",
volume = "15",
number = "26",
pages = "31459-31469",
doi = "10.1021/acsami.3c04498"
}

Krstajić Pajić, M. N., Dobrota, A. S., Mazare, A., Đurđić, S. Z., Hwang, I., Skorodumova, N. V., Manojlović, D. D., Vasilić, R., Pašti, I. A., Schmuki, P.,& Lačnjevac, U.. (2023). Activation of Osmium by the Surface Effects of Hydrogenated TiO2 Nanotube Arrays for Enhanced Hydrogen Evolution Reaction Performance. in ACS Applied Materials & Interfaces
American Chemical Society., 15(26), 31459-31469.
https://doi.org/10.1021/acsami.3c04498

Krstajić Pajić MN, Dobrota AS, Mazare A, Đurđić SZ, Hwang I, Skorodumova NV, Manojlović DD, Vasilić R, Pašti IA, Schmuki P, Lačnjevac U. Activation of Osmium by the Surface Effects of Hydrogenated TiO2 Nanotube Arrays for Enhanced Hydrogen Evolution Reaction Performance. in ACS Applied Materials & Interfaces. 2023;15(26):31459-31469.
doi:10.1021/acsami.3c04498 .

Krstajić Pajić, Mila N., Dobrota, Ana S., Mazare, Anca, Đurđić, Slađana Z., Hwang, Imgon, Skorodumova, Natalia V., Manojlović, Dragan D., Vasilić, Rastko, Pašti, Igor A., Schmuki, Patrik, Lačnjevac, Uroš, "Activation of Osmium by the Surface Effects of Hydrogenated TiO2 Nanotube Arrays for Enhanced Hydrogen Evolution Reaction Performance" in ACS Applied Materials & Interfaces, 15, no. 26 (2023):31459-31469,
https://doi.org/10.1021/acsami.3c04498 . .

TY  - JOUR
AU  - Lačnjevac, Uroš
AU  - Vasilić, Rastko
AU  - Dobrota, Ana S.
AU  - Đurđić, Slađana Z.
AU  - Tomanec, Ondřej
AU  - Zbořil, Radek
AU  - Mohajernia, Shiva
AU  - Nguyen, Nhat Truong
AU  - Skorodumova, Natalia
AU  - Manojlović, Dragan D.
AU  - Elezović, Nevenka
AU  - Pašti, Igor
AU  - Schmuki, Patrik
PY  - 2020
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/4288
AB  - Developing ultraefficient electrocatalytic materials for the hydrogen evolution reaction (HER) with low content of expensive platinum group metals (PGMs) via low-energy-input procedures is the key to the successful commercialization of green water electrolysis technologies for sustainable production of high-purity hydrogen. In this study, we report a facile room-temperature synthesis of ultrafine metallic Ir nanoparticles on conductive, proton-intercalated TiO2 nanotube (H-TNT) arrays via galvanic displacement. A series of experiments demonstrate that a controlled transformation of the H-TNT surface microstructure from neat open-top tubes to disordered nanostripe bundles (“nanograss”) is highly beneficial for providing an abundance of exposed Ir active sites. Consequently, for nanograss-engineered composites, outstanding HER activity metrics are achieved even at very low Ir(III) precursor concentrations. An optimum Ir@TNT cathode loaded with 5.7 μgIr cm−2 exhibits an overpotential of −63 mV at −100 mA cm−2 and a mass activity of 34 A mgIr−1 at −80 mV under acidic conditions, along with excellent catalytic durability and structural integrity. Density functional theory (DFT) simulations reveal that the hydrogen-rich TiO2 surface not only stabilizes the deposited Ir and weakens its H binding strength to a moderate intensity, but also actively takes part in the HER mechanism by refreshing the Ir catalytic sites near the Ir|H–TiO2 interface, thus substantially promoting H2 generation. The comprehensive characterization combined with theory provides an in-depth understanding of the electrocatalytic behavior of H-TNT supported PGM nanoparticles and demonstrates their high potential as competitive electrocatalyst systems for the HER.
PB  - Royal Society of Chemistry
T2  - Journal of Materials Chemistry A
T1  - High-performance hydrogen evolution electrocatalysis using proton-intercalated TiO2 nanotube arrays as interactive supports for Ir nanoparticles
VL  - 8
IS  - 43
SP  - 22773
EP  - 22790
DO  - 10.1039/D0TA07492F
ER  - 

@article{
author = "Lačnjevac, Uroš and Vasilić, Rastko and Dobrota, Ana S. and Đurđić, Slađana Z. and Tomanec, Ondřej and Zbořil, Radek and Mohajernia, Shiva and Nguyen, Nhat Truong and Skorodumova, Natalia and Manojlović, Dragan D. and Elezović, Nevenka and Pašti, Igor and Schmuki, Patrik",
year = "2020",
abstract = "Developing ultraefficient electrocatalytic materials for the hydrogen evolution reaction (HER) with low content of expensive platinum group metals (PGMs) via low-energy-input procedures is the key to the successful commercialization of green water electrolysis technologies for sustainable production of high-purity hydrogen. In this study, we report a facile room-temperature synthesis of ultrafine metallic Ir nanoparticles on conductive, proton-intercalated TiO2 nanotube (H-TNT) arrays via galvanic displacement. A series of experiments demonstrate that a controlled transformation of the H-TNT surface microstructure from neat open-top tubes to disordered nanostripe bundles (“nanograss”) is highly beneficial for providing an abundance of exposed Ir active sites. Consequently, for nanograss-engineered composites, outstanding HER activity metrics are achieved even at very low Ir(III) precursor concentrations. An optimum Ir@TNT cathode loaded with 5.7 μgIr cm−2 exhibits an overpotential of −63 mV at −100 mA cm−2 and a mass activity of 34 A mgIr−1 at −80 mV under acidic conditions, along with excellent catalytic durability and structural integrity. Density functional theory (DFT) simulations reveal that the hydrogen-rich TiO2 surface not only stabilizes the deposited Ir and weakens its H binding strength to a moderate intensity, but also actively takes part in the HER mechanism by refreshing the Ir catalytic sites near the Ir|H–TiO2 interface, thus substantially promoting H2 generation. The comprehensive characterization combined with theory provides an in-depth understanding of the electrocatalytic behavior of H-TNT supported PGM nanoparticles and demonstrates their high potential as competitive electrocatalyst systems for the HER.",
publisher = "Royal Society of Chemistry",
journal = "Journal of Materials Chemistry A",
title = "High-performance hydrogen evolution electrocatalysis using proton-intercalated TiO2 nanotube arrays as interactive supports for Ir nanoparticles",
volume = "8",
number = "43",
pages = "22773-22790",
doi = "10.1039/D0TA07492F"
}

Lačnjevac, U., Vasilić, R., Dobrota, A. S., Đurđić, S. Z., Tomanec, O., Zbořil, R., Mohajernia, S., Nguyen, N. T., Skorodumova, N., Manojlović, D. D., Elezović, N., Pašti, I.,& Schmuki, P.. (2020). High-performance hydrogen evolution electrocatalysis using proton-intercalated TiO2 nanotube arrays as interactive supports for Ir nanoparticles. in Journal of Materials Chemistry A
Royal Society of Chemistry., 8(43), 22773-22790.
https://doi.org/10.1039/D0TA07492F

Lačnjevac U, Vasilić R, Dobrota AS, Đurđić SZ, Tomanec O, Zbořil R, Mohajernia S, Nguyen NT, Skorodumova N, Manojlović DD, Elezović N, Pašti I, Schmuki P. High-performance hydrogen evolution electrocatalysis using proton-intercalated TiO2 nanotube arrays as interactive supports for Ir nanoparticles. in Journal of Materials Chemistry A. 2020;8(43):22773-22790.
doi:10.1039/D0TA07492F .

Lačnjevac, Uroš, Vasilić, Rastko, Dobrota, Ana S., Đurđić, Slađana Z., Tomanec, Ondřej, Zbořil, Radek, Mohajernia, Shiva, Nguyen, Nhat Truong, Skorodumova, Natalia, Manojlović, Dragan D., Elezović, Nevenka, Pašti, Igor, Schmuki, Patrik, "High-performance hydrogen evolution electrocatalysis using proton-intercalated TiO2 nanotube arrays as interactive supports for Ir nanoparticles" in Journal of Materials Chemistry A, 8, no. 43 (2020):22773-22790,
https://doi.org/10.1039/D0TA07492F . .

TY  - JOUR
AU  - Gavrilov, Nemanja
AU  - Momcilovic, Milan
AU  - Dobrota, Ana S.
AU  - Stanković, Dalibor
AU  - Jokić, Bojan
AU  - Babić, Biljana
AU  - Skorodumova, Natalia V.
AU  - Mentus, Slavko V.
AU  - Pasti, Igor A.
PY  - 2018
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2088
AB  - The incorporation of trace amounts ( lt  0.2%) of Co and Ni noticeably enhanced the catalytic activity of nitrogen free ordered mesoporous carbon (OMC) towards oxygen reduction reaction (ORR). (Co,Ni)-doped OMCs were characterized by N-2-adsorption measurements, X-ray powder diffraction, field emission scanning electron microscopy and Raman spectroscopy methods, and their ORR activity was estimated by voltammetry on rotating disk electrode in acidic and alkaline media. (Co,Ni)-doped OMCs show modest activities in acidic media, while the catalytic activity in alkaline media is rather high. The measured activities are compared to the Pt-based and Pt-free ORR catalysts reported in the literature. The number of electrons consumed per O-2 in metal-doped OMCs was found to vary between 2 and 4, which is advantageous in comparison to metal-free OMC. Also, the mass activities of metal-doped OMCs were found to be up to 2.5 times higher compared to that of metal-free OMC. We suggest that the ORR activity is governed by a balance between (i) textural properties, which determine the electrochemically accessible surface of the catalyst and which are influenced by the addition of a metal precursor, and (ii) novel active sites formed upon the introduction of metals into the carbon structure. In particular, our Density Functional Theory calculations suggest that Co and Ni atoms embedded into the single vacancies of graphene can activate the O-2 molecule and contribute to the decomposition of peroxide.
PB  - Elsevier Science Sa, Lausanne
T2  - Surface and Coatings Technology
T1  - A study of ordered mesoporous carbon doped with Co and Ni as a catalyst of oxygen reduction reaction in both alkaline and acidic media
VL  - 349
SP  - 511
EP  - 521
DO  - 10.1016/j.surfcoat.2018.06.008
ER  - 

@article{
author = "Gavrilov, Nemanja and Momcilovic, Milan and Dobrota, Ana S. and Stanković, Dalibor and Jokić, Bojan and Babić, Biljana and Skorodumova, Natalia V. and Mentus, Slavko V. and Pasti, Igor A.",
year = "2018",
abstract = "The incorporation of trace amounts ( lt  0.2%) of Co and Ni noticeably enhanced the catalytic activity of nitrogen free ordered mesoporous carbon (OMC) towards oxygen reduction reaction (ORR). (Co,Ni)-doped OMCs were characterized by N-2-adsorption measurements, X-ray powder diffraction, field emission scanning electron microscopy and Raman spectroscopy methods, and their ORR activity was estimated by voltammetry on rotating disk electrode in acidic and alkaline media. (Co,Ni)-doped OMCs show modest activities in acidic media, while the catalytic activity in alkaline media is rather high. The measured activities are compared to the Pt-based and Pt-free ORR catalysts reported in the literature. The number of electrons consumed per O-2 in metal-doped OMCs was found to vary between 2 and 4, which is advantageous in comparison to metal-free OMC. Also, the mass activities of metal-doped OMCs were found to be up to 2.5 times higher compared to that of metal-free OMC. We suggest that the ORR activity is governed by a balance between (i) textural properties, which determine the electrochemically accessible surface of the catalyst and which are influenced by the addition of a metal precursor, and (ii) novel active sites formed upon the introduction of metals into the carbon structure. In particular, our Density Functional Theory calculations suggest that Co and Ni atoms embedded into the single vacancies of graphene can activate the O-2 molecule and contribute to the decomposition of peroxide.",
publisher = "Elsevier Science Sa, Lausanne",
journal = "Surface and Coatings Technology",
title = "A study of ordered mesoporous carbon doped with Co and Ni as a catalyst of oxygen reduction reaction in both alkaline and acidic media",
volume = "349",
pages = "511-521",
doi = "10.1016/j.surfcoat.2018.06.008"
}

Gavrilov, N., Momcilovic, M., Dobrota, A. S., Stanković, D., Jokić, B., Babić, B., Skorodumova, N. V., Mentus, S. V.,& Pasti, I. A.. (2018). A study of ordered mesoporous carbon doped with Co and Ni as a catalyst of oxygen reduction reaction in both alkaline and acidic media. in Surface and Coatings Technology
Elsevier Science Sa, Lausanne., 349, 511-521.
https://doi.org/10.1016/j.surfcoat.2018.06.008

Gavrilov N, Momcilovic M, Dobrota AS, Stanković D, Jokić B, Babić B, Skorodumova NV, Mentus SV, Pasti IA. A study of ordered mesoporous carbon doped with Co and Ni as a catalyst of oxygen reduction reaction in both alkaline and acidic media. in Surface and Coatings Technology. 2018;349:511-521.
doi:10.1016/j.surfcoat.2018.06.008 .

Gavrilov, Nemanja, Momcilovic, Milan, Dobrota, Ana S., Stanković, Dalibor, Jokić, Bojan, Babić, Biljana, Skorodumova, Natalia V., Mentus, Slavko V., Pasti, Igor A., "A study of ordered mesoporous carbon doped with Co and Ni as a catalyst of oxygen reduction reaction in both alkaline and acidic media" in Surface and Coatings Technology, 349 (2018):511-521,
https://doi.org/10.1016/j.surfcoat.2018.06.008 . .

TY  - JOUR
AU  - Pasti, Igor A.
AU  - Gavrilov, Nemanja
AU  - Dobrota, Ana S.
AU  - Momcilovic, Milan
AU  - Stojmenovic, Marija
AU  - Topalov, Angel
AU  - Stanković, Dalibor
AU  - Babić, Biljana
AU  - Ćirić-Marjanović, Gordana
AU  - Mentus, Slavko V.
PY  - 2015
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/1980
AB  - In order to elucidate the role of B, N, and P dopants in carbon materials on the kinetics of oxygen reduction reaction (ORR) and to provide a fair comparison of the effects of each dopant, a series of ordered mesoporous carbons (OMCs) with low concentration of heteroatoms ( lt  1 at%) has been prepared. Doped OMCs were characterized using X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectroscopy (ICP-OES), Raman spectroscopy, X-ray powder diffraction (XRD), and N-2 physisorption measurements. Comparative study of the ORR activity of these materials in alkaline solution was performed using rotating disk electrode voltammetry. The experiments evidenced that, compared to non-doped OMC, charge transfer kinetics was improved independently on the nature of the heteroatom. The decrease of the ORR overvoltage and the increase of the mass activity upon doping are similar for B and P and less prominent for N. On the other hand, OMCs doped with low levels of B and N were found to be selective for O-2 reduction to peroxide, while for P-doped OMCs, the apparent number of electrons consumed per O-2 molecule was up to 3.1. Experimental measurements were complemented by density functional theory (DFT) calculations.
PB  - Springer, New York
T2  - Electrocatalysis
T1  - The Effects of a Low-Level Boron, Phosphorus, and Nitrogen Doping on the Oxygen Reduction Activity of Ordered Mesoporous Carbons
VL  - 6
IS  - 6
SP  - 498
EP  - 511
DO  - 10.1007/s12678-015-0271-0
ER  - 

@article{
author = "Pasti, Igor A. and Gavrilov, Nemanja and Dobrota, Ana S. and Momcilovic, Milan and Stojmenovic, Marija and Topalov, Angel and Stanković, Dalibor and Babić, Biljana and Ćirić-Marjanović, Gordana and Mentus, Slavko V.",
year = "2015",
abstract = "In order to elucidate the role of B, N, and P dopants in carbon materials on the kinetics of oxygen reduction reaction (ORR) and to provide a fair comparison of the effects of each dopant, a series of ordered mesoporous carbons (OMCs) with low concentration of heteroatoms ( lt  1 at%) has been prepared. Doped OMCs were characterized using X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectroscopy (ICP-OES), Raman spectroscopy, X-ray powder diffraction (XRD), and N-2 physisorption measurements. Comparative study of the ORR activity of these materials in alkaline solution was performed using rotating disk electrode voltammetry. The experiments evidenced that, compared to non-doped OMC, charge transfer kinetics was improved independently on the nature of the heteroatom. The decrease of the ORR overvoltage and the increase of the mass activity upon doping are similar for B and P and less prominent for N. On the other hand, OMCs doped with low levels of B and N were found to be selective for O-2 reduction to peroxide, while for P-doped OMCs, the apparent number of electrons consumed per O-2 molecule was up to 3.1. Experimental measurements were complemented by density functional theory (DFT) calculations.",
publisher = "Springer, New York",
journal = "Electrocatalysis",
title = "The Effects of a Low-Level Boron, Phosphorus, and Nitrogen Doping on the Oxygen Reduction Activity of Ordered Mesoporous Carbons",
volume = "6",
number = "6",
pages = "498-511",
doi = "10.1007/s12678-015-0271-0"
}

Pasti, I. A., Gavrilov, N., Dobrota, A. S., Momcilovic, M., Stojmenovic, M., Topalov, A., Stanković, D., Babić, B., Ćirić-Marjanović, G.,& Mentus, S. V.. (2015). The Effects of a Low-Level Boron, Phosphorus, and Nitrogen Doping on the Oxygen Reduction Activity of Ordered Mesoporous Carbons. in Electrocatalysis
Springer, New York., 6(6), 498-511.
https://doi.org/10.1007/s12678-015-0271-0

Pasti IA, Gavrilov N, Dobrota AS, Momcilovic M, Stojmenovic M, Topalov A, Stanković D, Babić B, Ćirić-Marjanović G, Mentus SV. The Effects of a Low-Level Boron, Phosphorus, and Nitrogen Doping on the Oxygen Reduction Activity of Ordered Mesoporous Carbons. in Electrocatalysis. 2015;6(6):498-511.
doi:10.1007/s12678-015-0271-0 .

Pasti, Igor A., Gavrilov, Nemanja, Dobrota, Ana S., Momcilovic, Milan, Stojmenovic, Marija, Topalov, Angel, Stanković, Dalibor, Babić, Biljana, Ćirić-Marjanović, Gordana, Mentus, Slavko V., "The Effects of a Low-Level Boron, Phosphorus, and Nitrogen Doping on the Oxygen Reduction Activity of Ordered Mesoporous Carbons" in Electrocatalysis, 6, no. 6 (2015):498-511,
https://doi.org/10.1007/s12678-015-0271-0 . .