Electrosorption of carbon dioxide on platinum group metals and alloys—a review

Łukaszewski, M.; Siwek, H.; Czerwiński, A.

doi:10.1007/s10008-008-0618-z

Cited by 26 publications

(27 citation statements)

References 114 publications

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“…Interestingly, the charge density recorded in the CO 2 ‐saturated electrolyte is approximately an order of magnitude lower than that in Ar‐saturated solution. This suggests that CO 2 adsorption inhibits the competing hydrogen processes . The systematic increase in charge density for CO 2 electrolysis at the CS1 electrocatalyst with variation in potential from −0.3 to −0.7 V is shown in Figure b.…”

Section: Resultssupporting

confidence: 93%

“…A similar effect was observed for Au‐Pd alloy electrodes, and linked to concomitant Pd‐hydride formation, which was more facile in alloys with a higher Pd content . Minor cathodic peaks can be seen between 0.3 and −0.3 V for CS5 and CS10, which could be linked to the adsorption of CO 2 to the catalyst surface . However, the most noticeable features for the thicker Pd layers correspond to the partial suppression of the H‐related responses in the positive scan up to approximately 0.4 V. In the case of Au nanoparticles and CS1, the differences in the voltammograms recorded with Ar‐ and CO 2 ‐saturated electrolytes in this potential range are rather minor.…”

Section: Resultsmentioning

confidence: 99%

“…The precise identity of the intermediate responsible for the voltammetric feature at 0.8 V remains to be elucidated fully, and other studies suggest adsorbed CO or a range of multi‐bonded CO radicals, such as (HCOO), CHO, C(OH) 2 and CH x . For the sake of simplicity, we shall refer to this feature as the “CO‐like” oxidation.…”

Section: Resultsmentioning

confidence: 99%

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Electrochemical Reduction of Carbon Dioxide at Gold‐Palladium Core–Shell Nanoparticles: Product Distribution versus Shell Thickness

et al. 2016

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The electrocatalytic reduction of CO2 at carbon-supported Au-Pd core-shell nanoparticles is systematically investigated as a function of Pd shell thickness. Liquid and gas phase products were determined by off-line 1 H NMR and on-line electrochemical mass spectrometry (OLEMS). Our results uncover the relationship between the nature of products generated and the Pd shell thickness. CO and H2 are the only products generated at 1 nm thick shells, while shells of 5 and 10 nm produced HCOO -, CH4 and C2H6. The concentration of HCOO -detected in the electrolyte was dependent on the applied potential, reaching a maximum Faradaic efficiency of 27% at -0.5 V vs. RHE for 10 nm thick shells. We conclude that collisions between absorbed hydrogen at relaxed Pd lattices and strongly bound "COlike" intermediates promote the complete hydrogenation to C1 and C2 alkanes, without the generation of other products such as alcohols and aldehydes.

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Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

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Electrochemical Reduction of Carbon Dioxide at Gold‐Palladium Core–Shell Nanoparticles: Product Distribution versus Shell Thickness

et al. 2016

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“…Even after 30 min of CO 2 exposure, the hydrogen desorption peak is only partially suppressed, which compares to a full coverage after 5 minutes of CO (2% in Ar) exposure at the same potential. 21 In accordance with earlier reports, 9,12,22,23 the subsequent stripping peak is found in the double layer region. The broader oxidation peak after CO 2 exposure at 80 • C appears at a slightly lower potential (≈0.55 V) than that of CO (≈0.62 V), indicating that the adsorbed layer differs somewhat from that formed by CO.…”

Section: Resultssupporting

confidence: 92%

Influence of Hydrogen and Operation Conditions on CO2 Adsorption on Pt and PtRu Catalyst in a PEMFC

Kortsdottir¹,

Domínguez²,

Lindström³

2013

ECS Electrochemistry Letters

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CO 2 is a major component in reformate gas and can, as a source of CO, be a catalyst poison in polymer electrolyte membrane fuel cells. The effect of CO 2 on cell performance is not fully understood in the presence of hydrogen. This paper addresses the influence of hydrogen on CO 2 adsorption on Pt/C and PtRu/C catalysts. The results show that the reduction and adsorption of CO 2 is slow but increases if hydrogen is present, especially on PtRu/C. Further, exposure to a CO 2 and H 2 mixture at 0.15 V on PtRu/C results in current oscillations, which are dependent on operation conditions. Reformate gas inevitably contains 10-30% CO 2 and traces of CO, even after several purification steps. While numerous studies exist on the influence of CO on fuel cell performance, see reviews 1-3 and references therein, the effect of CO 2 is less studied. Although CO 2 is potentially harmless in a fuel cell, studies have shown 4,5 that 20-25% CO 2 in the hydrogen fuel induces performance losses that cannot be explained by dilution only. It is generally argued that CO 2 is transformed to CO in the fuel cell, due to the reverse water-gas shift (RWGS) reaction 4or by an electrochemical reduction mechanism, 6 such asalthough the latter has been questioned due to its low standard potential of −0.2 V. 7 According to thermodynamic calculations the RWGS reaction would give rise to CO concentrations of about 15-100 ppm in equilibrium with a 20-25% CO 2 /H 2 gas mixture 2,8,9 depending on temperature and humidity. However, the moderate effects of CO 2 in operating fuel cells 8,10 indicates that much lower concentrations must be present, presumably due to slow kinetics of both the RWGS reaction 9,11 and the electroreduction of CO 2 8 at PEM fuel cell conditions. Using PtRu as a catalyst instead of Pt has been shown to improve the tolerance of CO 2 in the hydrogen gas, 4,5,9,12 but there is some controversy as to whether it is only due to the improved tolerance to CO,11,12 or if Ru somehow hinders the transformation of CO 2 to CO. 4,9 This study sheds further light on the interplay between hydrogen and CO 2 in a fuel cell both on Pt/C and PtRu/C catalyst and how this is affected by operation conditions, in particular the influence of relative humidity and the presence or absence of H 2 . ExperimentalMembrane electrode assemblies (MEA) were prepared using Tanaka catalysts (TEC10E40E, 36% Pt, and TEC61E54, 29.7% Pt and 23.0% Ru (1:1.5) both on high surface carbon) and N115 membranes, as previously described. 13,14 The experimental setup was identical to that used in a previous study, 14 with a cell housing from ElectroChem, Inc connected to a PAR potentiostat. The MEA was activated according to the previously described procedure, 13,14 except for the adjustment of the higher potential limit in the case of PtRu from 1.2 to 0.9 V, to avoid Ru oxidation and subsequent dissolution and loss of catalyst.As a standard experiment, CO 2 was allowed to enter the cell at a potential hold at 0.15 V for 30 min followed by a 5 min purge with N 2 . These time...

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“…As the applied potential exceeds the onset potential of the CO 2 reduction ( À 0.164 V), this reaction is activated. Essentially, two H þ are consumed for a CO formation as a result of one CO 2 molecule reduction 10,13,[27][28][29] . Thus, a fraction of both the existing H þ (from the electrolyte) and the electrons (on the catalyst surface) are consumed in CO 2 reduction reactions instead of HER reactions.…”

Section: Resultsmentioning

confidence: 99%