TY  - JOUR
AU  - Obradović, Maja D
AU  - Balanc, Bojana D.
AU  - Lačnjevac, Uroš
AU  - Gojković, Snežana Lj
PY  - 2021
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1458
AB  - Hydrated iridiumoxyhydroxide (IrOx) films were electrochemically deposited from an alkaline oxalic solution at constant anodic potentials and by applying a potential cycling protocol, in both cases with variation of the electrodeposition time. FromUV-vis spetroscopy of the solution for the deposition and their characterization it was concluded that a mixture of Ir(III)/Ir(IV) monomers participates in the deposition of IrOx film. X-ray photoelectron spectroscopy (XPS) of IrOx films indicated that both types of films contained hydrated Ir(IV) hydroxide as the dominant species, but in the film deposited by potential cycling the presence of the additional Ir(III) species was evident. The scanning electon microscopy (SEM) analysis of the surface morphology revealed that films deposited by potential cycling were more uniform than the films deposited at a constant potential. The amount of electrochemically active Ir-species on the surface of deposited IrOx films was estimated from the voltammetric charge of the Ir(III)/Ir(IV) transition. Depending on the film electrodeposition parameters, the values between 15 and 1080 nmol cm-2 were obtained. The electrochemically active surface area (ECSA) of IrOx films was calculated from cyclic voltammetry and electrochemical impedance spectroscopy (EIS) measurements and ranged from 3 to 131 cm(2) per 1 cm(2) of geometric surface area for various films. The activity and stability of IrOx films toward oxygen evolution reaction (OER) was investigated in 0.5 M H2SO4 solution under potentiostatic conditions. The intrinsic activity, stated as turnover frequency and specific current density normalized per ECSA, showed that the OER activity of IrOx films deposited by potential cycling are up to two and a half times higher than the activity of films deposited at a constant anodic potential. Potentiostatic stability test showed a decrease in OER current over time for both type of the films. Determination of ECSA, the amount of electroactive Ir species, XPS spectrum and SEM imaging after the test indicated that the decrease in OER activity was caused by partial dissolution and delamination of the film as well as by oxidation of highly active hydroxide Ir(III) species.
PB  - Elsevier Science Sa, Lausanne
T2  - Journal of Electroanalytical Chemistry
T1  - Electrochemically deposited iridium-oxide: Estimation of intrinsic activity and stability in oxygen evolution in acid solution
VL  - 881
DO  - 10.1016/j.jelechem.2020.114944
ER  - 

@article{
author = "Obradović, Maja D and Balanc, Bojana D. and Lačnjevac, Uroš and Gojković, Snežana Lj",
year = "2021",
abstract = "Hydrated iridiumoxyhydroxide (IrOx) films were electrochemically deposited from an alkaline oxalic solution at constant anodic potentials and by applying a potential cycling protocol, in both cases with variation of the electrodeposition time. FromUV-vis spetroscopy of the solution for the deposition and their characterization it was concluded that a mixture of Ir(III)/Ir(IV) monomers participates in the deposition of IrOx film. X-ray photoelectron spectroscopy (XPS) of IrOx films indicated that both types of films contained hydrated Ir(IV) hydroxide as the dominant species, but in the film deposited by potential cycling the presence of the additional Ir(III) species was evident. The scanning electon microscopy (SEM) analysis of the surface morphology revealed that films deposited by potential cycling were more uniform than the films deposited at a constant potential. The amount of electrochemically active Ir-species on the surface of deposited IrOx films was estimated from the voltammetric charge of the Ir(III)/Ir(IV) transition. Depending on the film electrodeposition parameters, the values between 15 and 1080 nmol cm-2 were obtained. The electrochemically active surface area (ECSA) of IrOx films was calculated from cyclic voltammetry and electrochemical impedance spectroscopy (EIS) measurements and ranged from 3 to 131 cm(2) per 1 cm(2) of geometric surface area for various films. The activity and stability of IrOx films toward oxygen evolution reaction (OER) was investigated in 0.5 M H2SO4 solution under potentiostatic conditions. The intrinsic activity, stated as turnover frequency and specific current density normalized per ECSA, showed that the OER activity of IrOx films deposited by potential cycling are up to two and a half times higher than the activity of films deposited at a constant anodic potential. Potentiostatic stability test showed a decrease in OER current over time for both type of the films. Determination of ECSA, the amount of electroactive Ir species, XPS spectrum and SEM imaging after the test indicated that the decrease in OER activity was caused by partial dissolution and delamination of the film as well as by oxidation of highly active hydroxide Ir(III) species.",
publisher = "Elsevier Science Sa, Lausanne",
journal = "Journal of Electroanalytical Chemistry",
title = "Electrochemically deposited iridium-oxide: Estimation of intrinsic activity and stability in oxygen evolution in acid solution",
volume = "881",
doi = "10.1016/j.jelechem.2020.114944"
}

Obradović, M. D., Balanc, B. D., Lačnjevac, U.,& Gojković, S. L.. (2021). Electrochemically deposited iridium-oxide: Estimation of intrinsic activity and stability in oxygen evolution in acid solution. in Journal of Electroanalytical Chemistry
Elsevier Science Sa, Lausanne., 881.
https://doi.org/10.1016/j.jelechem.2020.114944

Obradović MD, Balanc BD, Lačnjevac U, Gojković SL. Electrochemically deposited iridium-oxide: Estimation of intrinsic activity and stability in oxygen evolution in acid solution. in Journal of Electroanalytical Chemistry. 2021;881.
doi:10.1016/j.jelechem.2020.114944 .

Obradović, Maja D, Balanc, Bojana D., Lačnjevac, Uroš, Gojković, Snežana Lj, "Electrochemically deposited iridium-oxide: Estimation of intrinsic activity and stability in oxygen evolution in acid solution" in Journal of Electroanalytical Chemistry, 881 (2021),
https://doi.org/10.1016/j.jelechem.2020.114944 . .

TY  - JOUR
AU  - Obradović, Maja D
AU  - Lačnjevac, Uroš
AU  - Babić, Biljana M.
AU  - Ercius, P.
AU  - Radmilović, Velimir R
AU  - Krstajić, Nedeljko V
AU  - Gojković, Snežana Lj
PY  - 2015
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/856
AB  - Two binary Ru-Ti oxides, Rum Ti0.9O2 and Ru0.7Ti0.3O2, were synthesized by the sol-gel method and used as an electrocatalyst support. The system was characterized by XRD, EDS, TEM and cyclic voltammetry. The Rum Ti0.9O2 and Ru0.7Ti0.3O2 consist of two phases of anatase and rutile structure. An average size of the Pt nanoparticles supported on them is similar to 3.5 nm and they are deposited on both Ru and Ti-rich domains. The supports exhibited good conductivity and electrochemical stability. The onset potentials of COads oxidation on the synthesized catalysts and on commercial PtRu/C are similar to each other and lower than that on Pt/C. This suggests that in Pt/Rum Ti0.9O2 and Pt/Ru0(.7)Ti(0.3)O(2) the Pt nanoparticles are in close contact with Ru atoms from the support, which enables the bifunctional mechanism. The activity and stability of the catalysts for methanol oxidation were examined under potentiodynamic and potentiostatic conditions. While the activity of Pt/Rum Ti0.9O2 is unsatisfactory, the performance of Pt/Ru0.7Ti0.3O2 is comparable to PtRu/C. For example, in the potentiostatic test at 0.5 V the activities after 25 min are 0.035 mA cm(-2) and 0.022 mA cm(-2) for Pt/Ru0.7Ti0.3O2 and PtRu/C, respectively. In potentiodynamic test the activities at 0.5V after 250 cycles are around 0.02 mA cm(-2) for both catalysts.
PB  - Amsterdam : Elsevier
T2  - Applied Catalysis B-Environmental
T1  - RuxTi1-xO2 as the support for Pt nanoparticles: Electrocatalysis of methanol oxidation
EP  - 152
SP  - 144
VL  - 170
DO  - 10.1016/j.apcatb.2015.01.038
ER  - 

@article{
author = "Obradović, Maja D and Lačnjevac, Uroš and Babić, Biljana M. and Ercius, P. and Radmilović, Velimir R and Krstajić, Nedeljko V and Gojković, Snežana Lj",
year = "2015",
abstract = "Two binary Ru-Ti oxides, Rum Ti0.9O2 and Ru0.7Ti0.3O2, were synthesized by the sol-gel method and used as an electrocatalyst support. The system was characterized by XRD, EDS, TEM and cyclic voltammetry. The Rum Ti0.9O2 and Ru0.7Ti0.3O2 consist of two phases of anatase and rutile structure. An average size of the Pt nanoparticles supported on them is similar to 3.5 nm and they are deposited on both Ru and Ti-rich domains. The supports exhibited good conductivity and electrochemical stability. The onset potentials of COads oxidation on the synthesized catalysts and on commercial PtRu/C are similar to each other and lower than that on Pt/C. This suggests that in Pt/Rum Ti0.9O2 and Pt/Ru0(.7)Ti(0.3)O(2) the Pt nanoparticles are in close contact with Ru atoms from the support, which enables the bifunctional mechanism. The activity and stability of the catalysts for methanol oxidation were examined under potentiodynamic and potentiostatic conditions. While the activity of Pt/Rum Ti0.9O2 is unsatisfactory, the performance of Pt/Ru0.7Ti0.3O2 is comparable to PtRu/C. For example, in the potentiostatic test at 0.5 V the activities after 25 min are 0.035 mA cm(-2) and 0.022 mA cm(-2) for Pt/Ru0.7Ti0.3O2 and PtRu/C, respectively. In potentiodynamic test the activities at 0.5V after 250 cycles are around 0.02 mA cm(-2) for both catalysts.",
publisher = "Amsterdam : Elsevier",
journal = "Applied Catalysis B-Environmental",
title = "RuxTi1-xO2 as the support for Pt nanoparticles: Electrocatalysis of methanol oxidation",
pages = "152-144",
volume = "170",
doi = "10.1016/j.apcatb.2015.01.038"
}

Obradović, M. D., Lačnjevac, U., Babić, B. M., Ercius, P., Radmilović, V. R., Krstajić, N. V.,& Gojković, S. L.. (2015). RuxTi1-xO2 as the support for Pt nanoparticles: Electrocatalysis of methanol oxidation. in Applied Catalysis B-Environmental
Amsterdam : Elsevier., 170, 144-152.
https://doi.org/10.1016/j.apcatb.2015.01.038

Obradović MD, Lačnjevac U, Babić BM, Ercius P, Radmilović VR, Krstajić NV, Gojković SL. RuxTi1-xO2 as the support for Pt nanoparticles: Electrocatalysis of methanol oxidation. in Applied Catalysis B-Environmental. 2015;170:144-152.
doi:10.1016/j.apcatb.2015.01.038 .

Obradović, Maja D, Lačnjevac, Uroš, Babić, Biljana M., Ercius, P., Radmilović, Velimir R, Krstajić, Nedeljko V, Gojković, Snežana Lj, "RuxTi1-xO2 as the support for Pt nanoparticles: Electrocatalysis of methanol oxidation" in Applied Catalysis B-Environmental, 170 (2015):144-152,
https://doi.org/10.1016/j.apcatb.2015.01.038 . .

TY  - JOUR
AU  - Krstajic, Mila N
AU  - Obradović, Maja D
AU  - Babić, Biljana M.
AU  - Radmilović, Velimir R
AU  - Lačnjevac, Uroš
AU  - Krstajić, Nedeljko V
AU  - Gojković, Snežana Lj
PY  - 2013
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/640
AB  - Ru-doped SnO2 powder, (RuxSn1-x)O-2, with a Sn:Ru atomic ratio of 9:1 was synthesized and used as a support for Pt nanoparticles (30 mass % loading). The (RuxSn1-x)O-2 support and the Pt/(RuxSn1-x)O-2 catalyst were characterized by X-ray diffraction measurements, energy dispersive X-ray spectroscopy and transmission electron microscopy (TEM). The (RuxSn1-x)O-2 was found to be a two-phase material consisting of probably a solid solution of RuO2 in SnO2 and pure RuO2. The average Pt particle size determined by TEM was 5.3 nm. Cyclic voltammetry of Pt/(RuxSn1-x)O-2 indicated good conductivity of the support and displayed the usual features of Pt. The results of the electrochemical oxidation of COad, and methanol on Pt/(RuxSn1-x)O-2 were compared with those on commercial Pt/C and PtRu/C catalysts. Oxidation of COads on Pt/(RuxSn1-x)O-2 starts at lower positive potentials than on PtRu/C and Pt/C. Potentiodynamic polarization curves and chronoamperometric curves of methanol oxidation indicated higher initial activity of the Pt/(RuxSn1-x)O-2 catalyst compared to PtRu/C, but also a greater loss in current density over time. A potentiodynamic stability test of the catalysts revealed that deactivation of Pt/(RuxSn1-x)O-2 and Pt/C was primarily caused by poisoning of the Pt surface by residues of methanol oxidation, which mostly occurred during the first potential cycle. In the case of PtRu/C, the poisoning of the surface was minor and deactivation was caused by surface area loss of the PtRu.
PB  - Srpsko hemijsko društvo, Beograd
T2  - Journal of the Serbian Chemical Society
T1  - Electrochemical oxidation of methanol on Pt/(RuxSn1-x)O-2 nanocatalyst
EP  - 1716
IS  - 11
SP  - 1703
VL  - 78
DO  - 10.2298/JSC130718091K
ER  - 

@article{
author = "Krstajic, Mila N and Obradović, Maja D and Babić, Biljana M. and Radmilović, Velimir R and Lačnjevac, Uroš and Krstajić, Nedeljko V and Gojković, Snežana Lj",
year = "2013",
abstract = "Ru-doped SnO2 powder, (RuxSn1-x)O-2, with a Sn:Ru atomic ratio of 9:1 was synthesized and used as a support for Pt nanoparticles (30 mass % loading). The (RuxSn1-x)O-2 support and the Pt/(RuxSn1-x)O-2 catalyst were characterized by X-ray diffraction measurements, energy dispersive X-ray spectroscopy and transmission electron microscopy (TEM). The (RuxSn1-x)O-2 was found to be a two-phase material consisting of probably a solid solution of RuO2 in SnO2 and pure RuO2. The average Pt particle size determined by TEM was 5.3 nm. Cyclic voltammetry of Pt/(RuxSn1-x)O-2 indicated good conductivity of the support and displayed the usual features of Pt. The results of the electrochemical oxidation of COad, and methanol on Pt/(RuxSn1-x)O-2 were compared with those on commercial Pt/C and PtRu/C catalysts. Oxidation of COads on Pt/(RuxSn1-x)O-2 starts at lower positive potentials than on PtRu/C and Pt/C. Potentiodynamic polarization curves and chronoamperometric curves of methanol oxidation indicated higher initial activity of the Pt/(RuxSn1-x)O-2 catalyst compared to PtRu/C, but also a greater loss in current density over time. A potentiodynamic stability test of the catalysts revealed that deactivation of Pt/(RuxSn1-x)O-2 and Pt/C was primarily caused by poisoning of the Pt surface by residues of methanol oxidation, which mostly occurred during the first potential cycle. In the case of PtRu/C, the poisoning of the surface was minor and deactivation was caused by surface area loss of the PtRu.",
publisher = "Srpsko hemijsko društvo, Beograd",
journal = "Journal of the Serbian Chemical Society",
title = "Electrochemical oxidation of methanol on Pt/(RuxSn1-x)O-2 nanocatalyst",
pages = "1716-1703",
number = "11",
volume = "78",
doi = "10.2298/JSC130718091K"
}

Krstajic, M. N., Obradović, M. D., Babić, B. M., Radmilović, V. R., Lačnjevac, U., Krstajić, N. V.,& Gojković, S. L.. (2013). Electrochemical oxidation of methanol on Pt/(RuxSn1-x)O-2 nanocatalyst. in Journal of the Serbian Chemical Society
Srpsko hemijsko društvo, Beograd., 78(11), 1703-1716.
https://doi.org/10.2298/JSC130718091K

Krstajic MN, Obradović MD, Babić BM, Radmilović VR, Lačnjevac U, Krstajić NV, Gojković SL. Electrochemical oxidation of methanol on Pt/(RuxSn1-x)O-2 nanocatalyst. in Journal of the Serbian Chemical Society. 2013;78(11):1703-1716.
doi:10.2298/JSC130718091K .

Krstajic, Mila N, Obradović, Maja D, Babić, Biljana M., Radmilović, Velimir R, Lačnjevac, Uroš, Krstajić, Nedeljko V, Gojković, Snežana Lj, "Electrochemical oxidation of methanol on Pt/(RuxSn1-x)O-2 nanocatalyst" in Journal of the Serbian Chemical Society, 78, no. 11 (2013):1703-1716,
https://doi.org/10.2298/JSC130718091K . .

TY  - JOUR
AU  - Obradović, Maja D
AU  - Gojković, Snežana Lj
AU  - Elezović, Nevenka R.
AU  - Ercius, P
AU  - Radmilović, Velimir R
AU  - Vračar, Ljiljana M
AU  - Krstajić, Nedeljko V
PY  - 2012
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/513
AB  - The catalytic activity of WC/Pt electrocatalysts towards hydrogen oxidation reaction (HOR) in acid solution was studied. Tungsten carbide (WC) prepared by polycondensation of resorcinol and formaldehyde in the presence of ammonium metatungstate salt and CTABr surfactant was used as the support of a Pt electrocatalyst (WC/Pt). The obtained WC/Pt electrodes were characterized by XRD, HRTEM, EDS, EELS and electrochemical measurements. HRTEM analysis showed that the WC particles possess a core-shell structure with a metallic tungsten core and a shell composed of a mixture of tungsten carbides shell (WC and W2C). The WC/Pt catalyst is composed of well-dispersed sub-nanometer Pt clusters which consist of a few to several tens of Pt atoms. EELS measurements indicate that the WC particles function as nucleation sites for Pt nanoparticles. Based on the Tafel-Heyrovsky-Volmer mechanism the corresponding kinetic equations were derived to describe the HOR current-potential behavior over the entire potential region on RDE. The fitting showed that in the lower potential region HOR on Pt proceeds most likely via the Tafel-Volmer (TV) pathway. The kinetic results also showed that the WC/Pt(1%) when compared to the standard C/Pt(1%) electrode led to a remarkable enhancement of the hydrogen oxidation in an acidic medium, which was explained by H-spill-over between platinum and tungsten carbide.
PB  - Elsevier Science Sa, Lausanne
T2  - Journal of Electroanalytical Chemistry
T1  - The kinetics of the hydrogen oxidation reaction on WC/Pt catalyst with low content of Pt nano-particles
EP  - 32
SP  - 24
VL  - 671
DO  - 10.1016/j.jelechem.2012.01.026
ER  - 

@article{
author = "Obradović, Maja D and Gojković, Snežana Lj and Elezović, Nevenka R. and Ercius, P and Radmilović, Velimir R and Vračar, Ljiljana M and Krstajić, Nedeljko V",
year = "2012",
abstract = "The catalytic activity of WC/Pt electrocatalysts towards hydrogen oxidation reaction (HOR) in acid solution was studied. Tungsten carbide (WC) prepared by polycondensation of resorcinol and formaldehyde in the presence of ammonium metatungstate salt and CTABr surfactant was used as the support of a Pt electrocatalyst (WC/Pt). The obtained WC/Pt electrodes were characterized by XRD, HRTEM, EDS, EELS and electrochemical measurements. HRTEM analysis showed that the WC particles possess a core-shell structure with a metallic tungsten core and a shell composed of a mixture of tungsten carbides shell (WC and W2C). The WC/Pt catalyst is composed of well-dispersed sub-nanometer Pt clusters which consist of a few to several tens of Pt atoms. EELS measurements indicate that the WC particles function as nucleation sites for Pt nanoparticles. Based on the Tafel-Heyrovsky-Volmer mechanism the corresponding kinetic equations were derived to describe the HOR current-potential behavior over the entire potential region on RDE. The fitting showed that in the lower potential region HOR on Pt proceeds most likely via the Tafel-Volmer (TV) pathway. The kinetic results also showed that the WC/Pt(1%) when compared to the standard C/Pt(1%) electrode led to a remarkable enhancement of the hydrogen oxidation in an acidic medium, which was explained by H-spill-over between platinum and tungsten carbide.",
publisher = "Elsevier Science Sa, Lausanne",
journal = "Journal of Electroanalytical Chemistry",
title = "The kinetics of the hydrogen oxidation reaction on WC/Pt catalyst with low content of Pt nano-particles",
pages = "32-24",
volume = "671",
doi = "10.1016/j.jelechem.2012.01.026"
}

Obradović, M. D., Gojković, S. L., Elezović, N. R., Ercius, P., Radmilović, V. R., Vračar, L. M.,& Krstajić, N. V.. (2012). The kinetics of the hydrogen oxidation reaction on WC/Pt catalyst with low content of Pt nano-particles. in Journal of Electroanalytical Chemistry
Elsevier Science Sa, Lausanne., 671, 24-32.
https://doi.org/10.1016/j.jelechem.2012.01.026

Obradović MD, Gojković SL, Elezović NR, Ercius P, Radmilović VR, Vračar LM, Krstajić NV. The kinetics of the hydrogen oxidation reaction on WC/Pt catalyst with low content of Pt nano-particles. in Journal of Electroanalytical Chemistry. 2012;671:24-32.
doi:10.1016/j.jelechem.2012.01.026 .

Obradović, Maja D, Gojković, Snežana Lj, Elezović, Nevenka R., Ercius, P, Radmilović, Velimir R, Vračar, Ljiljana M, Krstajić, Nedeljko V, "The kinetics of the hydrogen oxidation reaction on WC/Pt catalyst with low content of Pt nano-particles" in Journal of Electroanalytical Chemistry, 671 (2012):24-32,
https://doi.org/10.1016/j.jelechem.2012.01.026 . .