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Effect of tungsten carbide in carbon Pt catalyst support on electrochemical oxygen reduction in acid solution

Uticaj prisustva volfram-karbida u ugljeničnom nosaču Pt nanočestica na elektrohemijsku redukciju kiseonika u kiselom rastvoru

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2013
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Authors
Obradović, Maja
Babić, Biljana M.
Krstajić, Nedeljko V.
Gojković, Snežana Lj.
Article (Published version)
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Abstract
Tungsten carbide was synthesized by calcination of carbon cryogel with embedded tungsten in a form of metatungstate. This material was used as a support for Pt nanoparticles. XRD pattern of W-C support indicated the presence of WC, W2C, and unreacted W, as well as graphitized carbon. According to previous TEM analysis of W-C support, it contains particles with core-shell structure, where the W particle was covered with the shell of a mixture of WC and W2C. The average Pt grain size calculated from XRD pattern was about 6 nm. A cyclic voltammogram of W-C support was recorded within the potential range relevant for its application as a catalyst support in fuel cells. The pair of anodic/cathodic peaks close to the negative potential limit could be ascribed to the intercalation of hydrogen within hydrous tungsten oxide, which is always present on the surface of WC in aqueous solutions. The cyclic voltammogram of Pt/W-C indicated that tungsten oxide species are present on tungsten carbide s...hell as well as on the surface of Pt nanoparticles. The Pt surface is only partially covered by hydrous tungsten oxide. Hydrogen intercalation in hydrous tungsten oxide is enhanced in the presence of Pt nanoparticles. Also, the presence of hydrated tungsten oxide leads to the decrease of OH chemisorbed on Pt surface. Stripping of underpotentially deposited copper was used for the assessment of Pt surface area and the specific surface area of Pt was estimated to be 41 m2 g-1. The electrochemical oxygen reduction reaction was examined on the synthesized Pt/W-C catalyst and compared with the results on the commercial Pt/C catalyst. It was found that the current densities at Pt/W-C were almost twice as high as those on Pt/C. The Tafel plots for both catalysts are characterized with two Tafel slopes: -0.060 V dec-1 at low current densities, and -0.120 V dec-1 at high current densities. From the rotational dependence of the reaction rate, it was found that oxygen reduction on both Pt/W-C and Pt/C follows the first order kinetics with respect to O2 and that four electrons are transferred per O2 molecule. The results show that the presence of tungsten carbide in support material, i.e. hydrous tungsten oxide on Pt surface, leads to promotion of oxygen reduction on the Pt/W-C catalyst. It was assumed that oxophilic hydrated tungsten oxide hinders OH adsorption on Pt surface, thus increasing Pt surface area available for O2 adsorption and its electrochemical reduction.

Sintetizovan je nosač katalizatora u kojem se na ugljeničnoj osnovi nalaze nanočestice metalnog volframa obavijene volfram-karbidom i na njega su nanete nanočestice Pt. Karakterizacija sintetizovanog uzorka cikličnom voltametrijom u kiseloj sredini ukazala je na oksidaciju volframovih vrsta iz nosača i formiranje hidratisanih oksidnih vrsta volframa na površini Pt. Elektrohemijska redukcija O2 u kiseloj sredini je ispitivana na sintetizovanom uzorku i rezultati su upoređeni sa komercijalnim katalizatorom u kojem su nanočestice Pt na nosaču od ugljenika razvijene površine. Pokazano je da redukcija O2, bez obzira na nosač katalizatora, sledi kinetiku prvog reda po O2 uz razmenu četiri elektrona, ali da su gustine struje veće u slučaju nosača sa volfram-karbidom. Povećana aktivnost sintetizovanog katalizatora je posledica prisustva oksofiličnih hidratisanih oksida volframa koji sprečavaju adsorpciju hidratisanog oksida na površini Pt i tako povećavaju površinu Pt dostupnu za adsorpciju i ...redukciju molekula kiseonika.

Keywords:
Pt nanoparticle / Catalyst support / Tungsten / Tungsten carbide / electrochemical oxygen reduction / Acid solution / Pt nanočestice / nosač katalizatora / volfram / volfram-karbid / elektrohemijska redukcija kiseonika / kiseli rastvor
Source:
Hemijska industrija, 2013, 67, 2, 303-311
Publisher:
  • Association of Chemical Engineers of Serbia
Funding / projects:
  • Development, characterization and application nanostructured and composite electrocatalysts and interactive supports for fuel cells and water electrolysis (RS-172054)

DOI: 10.2298/HEMIND120307063O

ISSN: 0367-598X

WoS: 000322208200013

Scopus: 2-s2.0-84877707706
[ Google Scholar ]
1
URI
http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2369
Collections
  • Radovi istraživača / Researchers’ publications (TMF)
Institution/Community
Tehnološko-metalurški fakultet
TY  - JOUR
AU  - Obradović, Maja
AU  - Babić, Biljana M.
AU  - Krstajić, Nedeljko V.
AU  - Gojković, Snežana Lj.
PY  - 2013
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2369
AB  - Tungsten carbide was synthesized by calcination of carbon cryogel with embedded tungsten in a form of metatungstate. This material was used as a support for Pt nanoparticles. XRD pattern of W-C support indicated the presence of WC, W2C, and unreacted W, as well as graphitized carbon. According to previous TEM analysis of W-C support, it contains particles with core-shell structure, where the W particle was covered with the shell of a mixture of WC and W2C. The average Pt grain size calculated from XRD pattern was about 6 nm. A cyclic voltammogram of W-C support was recorded within the potential range relevant for its application as a catalyst support in fuel cells. The pair of anodic/cathodic peaks close to the negative potential limit could be ascribed to the intercalation of hydrogen within hydrous tungsten oxide, which is always present on the surface of WC in aqueous solutions. The cyclic voltammogram of Pt/W-C indicated that tungsten oxide species are present on tungsten carbide shell as well as on the surface of Pt nanoparticles. The Pt surface is only partially covered by hydrous tungsten oxide. Hydrogen intercalation in hydrous tungsten oxide is enhanced in the presence of Pt nanoparticles. Also, the presence of hydrated tungsten oxide leads to the decrease of OH chemisorbed on Pt surface. Stripping of underpotentially deposited copper was used for the assessment of Pt surface area and the specific surface area of Pt was estimated to be 41 m2 g-1. The electrochemical oxygen reduction reaction was examined on the synthesized Pt/W-C catalyst and compared with the results on the commercial Pt/C catalyst. It was found that the current densities at Pt/W-C were almost twice as high as those on Pt/C. The Tafel plots for both catalysts are characterized with two Tafel slopes: -0.060 V dec-1 at low current densities, and -0.120 V dec-1 at high current densities. From the rotational dependence of the reaction rate, it was found that oxygen reduction on both Pt/W-C and Pt/C follows the first order kinetics with respect to O2 and that four electrons are transferred per O2 molecule. The results show that the presence of tungsten carbide in support material, i.e. hydrous tungsten oxide on Pt surface, leads to promotion of oxygen reduction on the Pt/W-C catalyst. It was assumed that oxophilic hydrated tungsten oxide hinders OH adsorption on Pt surface, thus increasing Pt surface area available for O2 adsorption and its electrochemical reduction.
AB  - Sintetizovan je nosač katalizatora u kojem se na ugljeničnoj osnovi nalaze nanočestice metalnog volframa obavijene volfram-karbidom i na njega su nanete nanočestice Pt. Karakterizacija sintetizovanog uzorka cikličnom voltametrijom u kiseloj sredini ukazala je na oksidaciju volframovih vrsta iz nosača i formiranje hidratisanih oksidnih vrsta volframa na površini Pt. Elektrohemijska redukcija O2 u kiseloj sredini je ispitivana na sintetizovanom uzorku i rezultati su upoređeni sa komercijalnim katalizatorom u kojem su nanočestice Pt na nosaču od ugljenika razvijene površine. Pokazano je da redukcija O2, bez obzira na nosač katalizatora, sledi kinetiku prvog reda po O2 uz razmenu četiri elektrona, ali da su gustine struje veće u slučaju nosača sa volfram-karbidom. Povećana aktivnost sintetizovanog katalizatora je posledica prisustva oksofiličnih hidratisanih oksida volframa koji sprečavaju adsorpciju hidratisanog oksida na površini Pt i tako povećavaju površinu Pt dostupnu za adsorpciju i redukciju molekula kiseonika.
PB  - Association of Chemical Engineers of Serbia
T2  - Hemijska industrija
T1  - Effect of tungsten carbide in carbon Pt catalyst support on electrochemical oxygen reduction in acid solution
T1  - Uticaj prisustva volfram-karbida u ugljeničnom nosaču Pt nanočestica na elektrohemijsku redukciju kiseonika u kiselom rastvoru
EP  - 311
IS  - 2
SP  - 303
VL  - 67
DO  - 10.2298/HEMIND120307063O
ER  - 
@article{
author = "Obradović, Maja and Babić, Biljana M. and Krstajić, Nedeljko V. and Gojković, Snežana Lj.",
year = "2013",
abstract = "Tungsten carbide was synthesized by calcination of carbon cryogel with embedded tungsten in a form of metatungstate. This material was used as a support for Pt nanoparticles. XRD pattern of W-C support indicated the presence of WC, W2C, and unreacted W, as well as graphitized carbon. According to previous TEM analysis of W-C support, it contains particles with core-shell structure, where the W particle was covered with the shell of a mixture of WC and W2C. The average Pt grain size calculated from XRD pattern was about 6 nm. A cyclic voltammogram of W-C support was recorded within the potential range relevant for its application as a catalyst support in fuel cells. The pair of anodic/cathodic peaks close to the negative potential limit could be ascribed to the intercalation of hydrogen within hydrous tungsten oxide, which is always present on the surface of WC in aqueous solutions. The cyclic voltammogram of Pt/W-C indicated that tungsten oxide species are present on tungsten carbide shell as well as on the surface of Pt nanoparticles. The Pt surface is only partially covered by hydrous tungsten oxide. Hydrogen intercalation in hydrous tungsten oxide is enhanced in the presence of Pt nanoparticles. Also, the presence of hydrated tungsten oxide leads to the decrease of OH chemisorbed on Pt surface. Stripping of underpotentially deposited copper was used for the assessment of Pt surface area and the specific surface area of Pt was estimated to be 41 m2 g-1. The electrochemical oxygen reduction reaction was examined on the synthesized Pt/W-C catalyst and compared with the results on the commercial Pt/C catalyst. It was found that the current densities at Pt/W-C were almost twice as high as those on Pt/C. The Tafel plots for both catalysts are characterized with two Tafel slopes: -0.060 V dec-1 at low current densities, and -0.120 V dec-1 at high current densities. From the rotational dependence of the reaction rate, it was found that oxygen reduction on both Pt/W-C and Pt/C follows the first order kinetics with respect to O2 and that four electrons are transferred per O2 molecule. The results show that the presence of tungsten carbide in support material, i.e. hydrous tungsten oxide on Pt surface, leads to promotion of oxygen reduction on the Pt/W-C catalyst. It was assumed that oxophilic hydrated tungsten oxide hinders OH adsorption on Pt surface, thus increasing Pt surface area available for O2 adsorption and its electrochemical reduction., Sintetizovan je nosač katalizatora u kojem se na ugljeničnoj osnovi nalaze nanočestice metalnog volframa obavijene volfram-karbidom i na njega su nanete nanočestice Pt. Karakterizacija sintetizovanog uzorka cikličnom voltametrijom u kiseloj sredini ukazala je na oksidaciju volframovih vrsta iz nosača i formiranje hidratisanih oksidnih vrsta volframa na površini Pt. Elektrohemijska redukcija O2 u kiseloj sredini je ispitivana na sintetizovanom uzorku i rezultati su upoređeni sa komercijalnim katalizatorom u kojem su nanočestice Pt na nosaču od ugljenika razvijene površine. Pokazano je da redukcija O2, bez obzira na nosač katalizatora, sledi kinetiku prvog reda po O2 uz razmenu četiri elektrona, ali da su gustine struje veće u slučaju nosača sa volfram-karbidom. Povećana aktivnost sintetizovanog katalizatora je posledica prisustva oksofiličnih hidratisanih oksida volframa koji sprečavaju adsorpciju hidratisanog oksida na površini Pt i tako povećavaju površinu Pt dostupnu za adsorpciju i redukciju molekula kiseonika.",
publisher = "Association of Chemical Engineers of Serbia",
journal = "Hemijska industrija",
title = "Effect of tungsten carbide in carbon Pt catalyst support on electrochemical oxygen reduction in acid solution, Uticaj prisustva volfram-karbida u ugljeničnom nosaču Pt nanočestica na elektrohemijsku redukciju kiseonika u kiselom rastvoru",
pages = "311-303",
number = "2",
volume = "67",
doi = "10.2298/HEMIND120307063O"
}
Obradović, M., Babić, B. M., Krstajić, N. V.,& Gojković, S. Lj.. (2013). Effect of tungsten carbide in carbon Pt catalyst support on electrochemical oxygen reduction in acid solution. in Hemijska industrija
Association of Chemical Engineers of Serbia., 67(2), 303-311.
https://doi.org/10.2298/HEMIND120307063O
Obradović M, Babić BM, Krstajić NV, Gojković SL. Effect of tungsten carbide in carbon Pt catalyst support on electrochemical oxygen reduction in acid solution. in Hemijska industrija. 2013;67(2):303-311.
doi:10.2298/HEMIND120307063O .
Obradović, Maja, Babić, Biljana M., Krstajić, Nedeljko V., Gojković, Snežana Lj., "Effect of tungsten carbide in carbon Pt catalyst support on electrochemical oxygen reduction in acid solution" in Hemijska industrija, 67, no. 2 (2013):303-311,
https://doi.org/10.2298/HEMIND120307063O . .

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