TY  - CONF
AU  - Lačnjevac, Uroš
AU  - Vasilic, Rastko
AU  - Dobrota, Ana S.
AU  - Đurđić, Slađana
AU  - Tomanec, Ondřej
AU  - Zbořil, Radek
AU  - Mohajernia, Shiva
AU  - Nguyen, Nhat Truong
AU  - Skorodumova, Natalia
AU  - Manojlović, Dragan
AU  - Elezović, Nevenka R.
AU  - Pasti, Igor
AU  - Schmuki, Patrik
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2843
AB  - Designing cost-effective hydrogen evolution reaction (HER) electrocatalysts containing highly active, but expensive platinum group metals (PGMs) is key to the commercialization of polymer electrolyte membrane water electrolysis systems for green hydrogen production. Our recent investigations have shown that efficient and durable HER composite cathodes can be prepared by spontaneous deposition of PGM nanoparticles on self-aligned titania nanotube (TNT) arrays formed by anodization [1]. In this synthesis route, anatase TNTs are first cathodically protonated (H-TNT), and then used as the reducing agent for PGM ions at room temperature. Herein, we employ the galvanic displacement strategy to decorate H-TNT arrays with ultrafine Ir nanoparticles [2]. We demonstrate that transforming the top surface morphology of supporting TNT arrays from ordered open-top tubes to bundled nanowires (“nanograss”) is beneficial for exposing more Ir active centers during the HER operation. Consequently, applying very low concentrations of Ir(III) ions in the galvanic displacement step is sufficient to produce exceptionally active nanograss-modified Ir@TNT composites. An optimum Ir@TNT, possessing a low Ir loading of 5.7 μgIr cm–2, requires an overpotential of only –63 mV to reach a current density of –100 mA cm–2 and shows a stable long-term performance in a 1 M HClO4 solution. Computational simulations suggest that the hydrogen-rich TiO2 support not only strongly interacts with anchored Ir particles and weakens their H binding strength to a moderate level, but also actively provides hydrogen for rejuvenation of the Ir active sites at the Ir|H-TiO2 interface, thereby significantly enhancing HER catalysis.

[1] U.Č. Lačnjevac, R. Vasilić, T. Tokarski, G. Cios, P. Żabiński, N. Elezović and N. V. Krstajić, Nano Energy 47 (2018) 527.
[2] U. Lačnjevac, R. Vasilić, A. Dobrota, S. Đurđić, O. Tomanec, R. Zbořil, S. Mohajernia, N.T. Nguyen, N. Skorodumova, D. Manojlović, N. Elezović, I. Pašti, P. Schmuki, Journal of Materials Chemistry A 8 (2020) 22773.
PB  - Belgrade : Institute for Multidisciplinary Research
C3  - Programme and the Book of Abstracts / 7th Conference of The Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023 Belgrade, Serbia
T1  - TiO2 nanotube arrays decorated with Ir nanoparticles for enhanced hydrogen evolution electrocatalysis
EP  - 74
SP  - 73
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2843
ER  - 

@conference{
author = "Lačnjevac, Uroš and Vasilic, Rastko and Dobrota, Ana S. and Đurđić, Slađana and Tomanec, Ondřej and Zbořil, Radek and Mohajernia, Shiva and Nguyen, Nhat Truong and Skorodumova, Natalia and Manojlović, Dragan and Elezović, Nevenka R. and Pasti, Igor and Schmuki, Patrik",
year = "2023",
abstract = "Designing cost-effective hydrogen evolution reaction (HER) electrocatalysts containing highly active, but expensive platinum group metals (PGMs) is key to the commercialization of polymer electrolyte membrane water electrolysis systems for green hydrogen production. Our recent investigations have shown that efficient and durable HER composite cathodes can be prepared by spontaneous deposition of PGM nanoparticles on self-aligned titania nanotube (TNT) arrays formed by anodization [1]. In this synthesis route, anatase TNTs are first cathodically protonated (H-TNT), and then used as the reducing agent for PGM ions at room temperature. Herein, we employ the galvanic displacement strategy to decorate H-TNT arrays with ultrafine Ir nanoparticles [2]. We demonstrate that transforming the top surface morphology of supporting TNT arrays from ordered open-top tubes to bundled nanowires (“nanograss”) is beneficial for exposing more Ir active centers during the HER operation. Consequently, applying very low concentrations of Ir(III) ions in the galvanic displacement step is sufficient to produce exceptionally active nanograss-modified Ir@TNT composites. An optimum Ir@TNT, possessing a low Ir loading of 5.7 μgIr cm–2, requires an overpotential of only –63 mV to reach a current density of –100 mA cm–2 and shows a stable long-term performance in a 1 M HClO4 solution. Computational simulations suggest that the hydrogen-rich TiO2 support not only strongly interacts with anchored Ir particles and weakens their H binding strength to a moderate level, but also actively provides hydrogen for rejuvenation of the Ir active sites at the Ir|H-TiO2 interface, thereby significantly enhancing HER catalysis.

[1] U.Č. Lačnjevac, R. Vasilić, T. Tokarski, G. Cios, P. Żabiński, N. Elezović and N. V. Krstajić, Nano Energy 47 (2018) 527.
[2] U. Lačnjevac, R. Vasilić, A. Dobrota, S. Đurđić, O. Tomanec, R. Zbořil, S. Mohajernia, N.T. Nguyen, N. Skorodumova, D. Manojlović, N. Elezović, I. Pašti, P. Schmuki, Journal of Materials Chemistry A 8 (2020) 22773.",
publisher = "Belgrade : Institute for Multidisciplinary Research",
journal = "Programme and the Book of Abstracts / 7th Conference of The Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023 Belgrade, Serbia",
title = "TiO2 nanotube arrays decorated with Ir nanoparticles for enhanced hydrogen evolution electrocatalysis",
pages = "74-73",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2843"
}

Lačnjevac, U., Vasilic, R., Dobrota, A. S., Đurđić, S., Tomanec, O., Zbořil, R., Mohajernia, S., Nguyen, N. T., Skorodumova, N., Manojlović, D., Elezović, N. R., Pasti, I.,& Schmuki, P.. (2023). TiO2 nanotube arrays decorated with Ir nanoparticles for enhanced hydrogen evolution electrocatalysis. in Programme and the Book of Abstracts / 7th Conference of The Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023 Belgrade, Serbia
Belgrade : Institute for Multidisciplinary Research., 73-74.
https://hdl.handle.net/21.15107/rcub_rimsi_2843

Lačnjevac U, Vasilic R, Dobrota AS, Đurđić S, Tomanec O, Zbořil R, Mohajernia S, Nguyen NT, Skorodumova N, Manojlović D, Elezović NR, Pasti I, Schmuki P. TiO2 nanotube arrays decorated with Ir nanoparticles for enhanced hydrogen evolution electrocatalysis. in Programme and the Book of Abstracts / 7th Conference of The Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023 Belgrade, Serbia. 2023;:73-74.
https://hdl.handle.net/21.15107/rcub_rimsi_2843 .

Lačnjevac, Uroš, Vasilic, Rastko, Dobrota, Ana S., Đurđić, Slađana, Tomanec, Ondřej, Zbořil, Radek, Mohajernia, Shiva, Nguyen, Nhat Truong, Skorodumova, Natalia, Manojlović, Dragan, Elezović, Nevenka R., Pasti, Igor, Schmuki, Patrik, "TiO2 nanotube arrays decorated with Ir nanoparticles for enhanced hydrogen evolution electrocatalysis" in Programme and the Book of Abstracts / 7th Conference of The Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023 Belgrade, Serbia (2023):73-74,
https://hdl.handle.net/21.15107/rcub_rimsi_2843 .

TY  - JOUR
AU  - Krstajić Pajić, Mila N.
AU  - Dobrota, Ana S.
AU  - Mazare, Anca
AU  - Đurđić, Slađana
AU  - Hwang, Imgon
AU  - Skorodumova, Natalia V.
AU  - Manojlović, Dragan
AU  - Vasilic, Rastko
AU  - Pašti, Igor A.
AU  - Schmuki, Patrik
AU  - Lačnjevac, Uroš
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2706
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 and Interfaces
T1  - Activation of Osmium by the Surface Effects of Hydrogenated TiO2 Nanotube Arrays for Enhanced Hydrogen Evolution Reaction Performance
EP  - 31469
IS  - 26
SP  - 31459
VL  - 15
DO  - 10.1021/acsami.3c04498
ER  - 

@article{
author = "Krstajić Pajić, Mila N. and Dobrota, Ana S. and Mazare, Anca and Đurđić, Slađana and Hwang, Imgon and Skorodumova, Natalia V. and Manojlović, Dragan and Vasilic, 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 and Interfaces",
title = "Activation of Osmium by the Surface Effects of Hydrogenated TiO2 Nanotube Arrays for Enhanced Hydrogen Evolution Reaction Performance",
pages = "31469-31459",
number = "26",
volume = "15",
doi = "10.1021/acsami.3c04498"
}

Krstajić Pajić, M. N., Dobrota, A. S., Mazare, A., Đurđić, S., Hwang, I., Skorodumova, N. V., Manojlović, D., Vasilic, 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 and Interfaces
American Chemical Society., 15(26), 31459-31469.
https://doi.org/10.1021/acsami.3c04498

Krstajić Pajić MN, Dobrota AS, Mazare A, Đurđić S, Hwang I, Skorodumova NV, Manojlović D, Vasilic 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 and Interfaces. 2023;15(26):31459-31469.
doi:10.1021/acsami.3c04498 .

Krstajić Pajić, Mila N., Dobrota, Ana S., Mazare, Anca, Đurđić, Slađana, Hwang, Imgon, Skorodumova, Natalia V., Manojlović, Dragan, Vasilic, 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 and Interfaces, 15, no. 26 (2023):31459-31469,
https://doi.org/10.1021/acsami.3c04498 . .

TY  - CONF
AU  - Lačnjevac, Uroš
PY  - 2022
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2834
AB  - Razvoj efikasnih elektrokatalizatora za reakciju izdvajanja vodonika sa niskim sadržajem skupocenih metala platinske grupe je ključan za širu komercijalizaciju elektrolizera vode sa polimernom membranom u kiseloj sredini. U ovom radu su anodno formirani nizovi TiO2 nanotuba (TNT) najpre katodno redukovani uz delimičnu interkalaciju protona, a zatim dekorisani ultrafinim česticama iridijuma putem direktne galvanske izmene. Pokazano je da kontrolisana transformacija morfologije gornje površine TNT filma od uredno poređanih otvorenih tuba do neuređenih nanožica kasnije doprinosi povećanju broja dostupnih aktivnih mesta Ir. Za Ir@TNT kompozite sa slojem nanožica, visoka aktivnost za izdvajanje vodonika postignuta je već pri korišćenju veoma niskih koncentracija IrCl3 u rastvoru za galvansku izmenu. Sa sadržajem Ir od svega 5.7 μg cm–2, najbolja Ir@TNT katoda pokazala je prenapetost od –63 mV na gustini struje od –100 mA cm–2, kao i izvrsnu katalitičku i strukturnu stabilnost u rastvoru 1 M HClO4. Teorijske simulacije sugerišu da hidrogenovani TiO2 nosač stabilizuje istaloženi Ir, omogućava umerenu jačinu veze Ir–Hads i aktivno regeneriše površinu Ir tokom izdvajanja vodonika.
PB  - Beograd : Univerzitet u Beogradu - Fakultet za fizičku hemiju
C3  - Савремени правци истраживања водоника као горива будућности, 10. јун 2022, Српска академија наука и уметности, Књига сажетака
T1  - Nanočestice iridijuma spontano istaložene na protonovane TiO2 nanotubularne strukture kao visokoaktivni elektrokatalizatori izdvajanja vodonika u kiseloj sredini
T1  - Iridium nanoparticles spontaneously deposited on protonated TiO2 nanotubular structures as highly active electrocatalysts for hydrogen evolution in acidic environment
SP  - 53
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2834
ER  - 

@conference{
author = "Lačnjevac, Uroš",
year = "2022",
abstract = "Razvoj efikasnih elektrokatalizatora za reakciju izdvajanja vodonika sa niskim sadržajem skupocenih metala platinske grupe je ključan za širu komercijalizaciju elektrolizera vode sa polimernom membranom u kiseloj sredini. U ovom radu su anodno formirani nizovi TiO2 nanotuba (TNT) najpre katodno redukovani uz delimičnu interkalaciju protona, a zatim dekorisani ultrafinim česticama iridijuma putem direktne galvanske izmene. Pokazano je da kontrolisana transformacija morfologije gornje površine TNT filma od uredno poređanih otvorenih tuba do neuređenih nanožica kasnije doprinosi povećanju broja dostupnih aktivnih mesta Ir. Za Ir@TNT kompozite sa slojem nanožica, visoka aktivnost za izdvajanje vodonika postignuta je već pri korišćenju veoma niskih koncentracija IrCl3 u rastvoru za galvansku izmenu. Sa sadržajem Ir od svega 5.7 μg cm–2, najbolja Ir@TNT katoda pokazala je prenapetost od –63 mV na gustini struje od –100 mA cm–2, kao i izvrsnu katalitičku i strukturnu stabilnost u rastvoru 1 M HClO4. Teorijske simulacije sugerišu da hidrogenovani TiO2 nosač stabilizuje istaloženi Ir, omogućava umerenu jačinu veze Ir–Hads i aktivno regeneriše površinu Ir tokom izdvajanja vodonika.",
publisher = "Beograd : Univerzitet u Beogradu - Fakultet za fizičku hemiju",
journal = "Савремени правци истраживања водоника као горива будућности, 10. јун 2022, Српска академија наука и уметности, Књига сажетака",
title = "Nanočestice iridijuma spontano istaložene na protonovane TiO2 nanotubularne strukture kao visokoaktivni elektrokatalizatori izdvajanja vodonika u kiseloj sredini, Iridium nanoparticles spontaneously deposited on protonated TiO2 nanotubular structures as highly active electrocatalysts for hydrogen evolution in acidic environment",
pages = "53",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2834"
}

Lačnjevac, U.. (2022). Nanočestice iridijuma spontano istaložene na protonovane TiO2 nanotubularne strukture kao visokoaktivni elektrokatalizatori izdvajanja vodonika u kiseloj sredini. in Савремени правци истраживања водоника као горива будућности, 10. јун 2022, Српска академија наука и уметности, Књига сажетака
Beograd : Univerzitet u Beogradu - Fakultet za fizičku hemiju., 53.
https://hdl.handle.net/21.15107/rcub_rimsi_2834

Lačnjevac U. Nanočestice iridijuma spontano istaložene na protonovane TiO2 nanotubularne strukture kao visokoaktivni elektrokatalizatori izdvajanja vodonika u kiseloj sredini. in Савремени правци истраживања водоника као горива будућности, 10. јун 2022, Српска академија наука и уметности, Књига сажетака. 2022;:53.
https://hdl.handle.net/21.15107/rcub_rimsi_2834 .

Lačnjevac, Uroš, "Nanočestice iridijuma spontano istaložene na protonovane TiO2 nanotubularne strukture kao visokoaktivni elektrokatalizatori izdvajanja vodonika u kiseloj sredini" in Савремени правци истраживања водоника као горива будућности, 10. јун 2022, Српска академија наука и уметности, Књига сажетака (2022):53,
https://hdl.handle.net/21.15107/rcub_rimsi_2834 .