Electrooxidation of H-2, CO, and H-2/CO mixtures on a well-characterized Pt70Mo30 bulk alloy electrode
Abstract
The electrochemical oxidation of hydrogen (H-2), carbon monoxide (CO), and their mixtures (500 ppm-2%) on a well-characterized Pt70Mo30 bulk alloy was examined using the rotating disk electrode technique in 0.5 M H2SO4 at 333 K, The electrodes were transferred to and from a UHV chamber, where surface analyses were conducted using a combination of low-energy ion scattering (LEIS), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). The surface composition of this alloy after sputter-etching and annealing in UHV was slightly enriched in Pt to a composition of Pt77Mo23 The kinetics of H-2 oxidation are not measurably affected by the presence of the Mo in the surface. The shapes of the polarization curves for the oxidation of the H-2/CO mixtures are qualitatively similar to those for the Pt50Ru50 alloy examined previously: a high current-potential slope ica. 0.5 V/dec at low overpotential followed by a transition to a highly active state when the current approach...es the diffusion-limiting current; the potential where the transition to the active state occurs decreases with decreasing CO concentration and decreases with increasing temperature; the current in the low-overpotential region is roughly inverse half-order in the CO partial pressure. The current densities in the low-overpotential region an comparable to those on Pt50Ru50 alloy and about a factor Or 50 times those on a pure rt surface, while the anodic stripping of irreversibly adsorbed CO is very different from that on the Pt50Ru50 alloy, with most of the COads being oxidized only above 0.6 V (RHE), there is direct evidence for the oxidation of small amounts of COads in the low-overpotential region of 0.05-0.5 V. The mechanism of action of Mo in the Pt surface in enhancing Hr oxidation in the presence of CO thus appears to be very similar to that of Ru: a reduction in the steady-state coverage of COads on the Pt sites by oxidative removal, freeing Pt sites for H-2 oxidation.
Source:
Journal of Physical Chemistry B, 1998, 102, 14, 2494-2501Publisher:
- Amer Chemical Soc, Washington
DOI: 10.1021/jp972692s
ISSN: 1089-5647
WoS: 000073043700008
Scopus: 2-s2.0-0000614988
Institution/Community
Tehnološko-metalurški fakultetTY - JOUR AU - Grgur, Branimir AU - Marković, NM AU - Ross, PN PY - 1998 UR - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/188 AB - The electrochemical oxidation of hydrogen (H-2), carbon monoxide (CO), and their mixtures (500 ppm-2%) on a well-characterized Pt70Mo30 bulk alloy was examined using the rotating disk electrode technique in 0.5 M H2SO4 at 333 K, The electrodes were transferred to and from a UHV chamber, where surface analyses were conducted using a combination of low-energy ion scattering (LEIS), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). The surface composition of this alloy after sputter-etching and annealing in UHV was slightly enriched in Pt to a composition of Pt77Mo23 The kinetics of H-2 oxidation are not measurably affected by the presence of the Mo in the surface. The shapes of the polarization curves for the oxidation of the H-2/CO mixtures are qualitatively similar to those for the Pt50Ru50 alloy examined previously: a high current-potential slope ica. 0.5 V/dec at low overpotential followed by a transition to a highly active state when the current approaches the diffusion-limiting current; the potential where the transition to the active state occurs decreases with decreasing CO concentration and decreases with increasing temperature; the current in the low-overpotential region is roughly inverse half-order in the CO partial pressure. The current densities in the low-overpotential region an comparable to those on Pt50Ru50 alloy and about a factor Or 50 times those on a pure rt surface, while the anodic stripping of irreversibly adsorbed CO is very different from that on the Pt50Ru50 alloy, with most of the COads being oxidized only above 0.6 V (RHE), there is direct evidence for the oxidation of small amounts of COads in the low-overpotential region of 0.05-0.5 V. The mechanism of action of Mo in the Pt surface in enhancing Hr oxidation in the presence of CO thus appears to be very similar to that of Ru: a reduction in the steady-state coverage of COads on the Pt sites by oxidative removal, freeing Pt sites for H-2 oxidation. PB - Amer Chemical Soc, Washington T2 - Journal of Physical Chemistry B T1 - Electrooxidation of H-2, CO, and H-2/CO mixtures on a well-characterized Pt70Mo30 bulk alloy electrode EP - 2501 IS - 14 SP - 2494 VL - 102 DO - 10.1021/jp972692s ER -
@article{ author = "Grgur, Branimir and Marković, NM and Ross, PN", year = "1998", abstract = "The electrochemical oxidation of hydrogen (H-2), carbon monoxide (CO), and their mixtures (500 ppm-2%) on a well-characterized Pt70Mo30 bulk alloy was examined using the rotating disk electrode technique in 0.5 M H2SO4 at 333 K, The electrodes were transferred to and from a UHV chamber, where surface analyses were conducted using a combination of low-energy ion scattering (LEIS), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). The surface composition of this alloy after sputter-etching and annealing in UHV was slightly enriched in Pt to a composition of Pt77Mo23 The kinetics of H-2 oxidation are not measurably affected by the presence of the Mo in the surface. The shapes of the polarization curves for the oxidation of the H-2/CO mixtures are qualitatively similar to those for the Pt50Ru50 alloy examined previously: a high current-potential slope ica. 0.5 V/dec at low overpotential followed by a transition to a highly active state when the current approaches the diffusion-limiting current; the potential where the transition to the active state occurs decreases with decreasing CO concentration and decreases with increasing temperature; the current in the low-overpotential region is roughly inverse half-order in the CO partial pressure. The current densities in the low-overpotential region an comparable to those on Pt50Ru50 alloy and about a factor Or 50 times those on a pure rt surface, while the anodic stripping of irreversibly adsorbed CO is very different from that on the Pt50Ru50 alloy, with most of the COads being oxidized only above 0.6 V (RHE), there is direct evidence for the oxidation of small amounts of COads in the low-overpotential region of 0.05-0.5 V. The mechanism of action of Mo in the Pt surface in enhancing Hr oxidation in the presence of CO thus appears to be very similar to that of Ru: a reduction in the steady-state coverage of COads on the Pt sites by oxidative removal, freeing Pt sites for H-2 oxidation.", publisher = "Amer Chemical Soc, Washington", journal = "Journal of Physical Chemistry B", title = "Electrooxidation of H-2, CO, and H-2/CO mixtures on a well-characterized Pt70Mo30 bulk alloy electrode", pages = "2501-2494", number = "14", volume = "102", doi = "10.1021/jp972692s" }
Grgur, B., Marković, N.,& Ross, P.. (1998). Electrooxidation of H-2, CO, and H-2/CO mixtures on a well-characterized Pt70Mo30 bulk alloy electrode. in Journal of Physical Chemistry B Amer Chemical Soc, Washington., 102(14), 2494-2501. https://doi.org/10.1021/jp972692s
Grgur B, Marković N, Ross P. Electrooxidation of H-2, CO, and H-2/CO mixtures on a well-characterized Pt70Mo30 bulk alloy electrode. in Journal of Physical Chemistry B. 1998;102(14):2494-2501. doi:10.1021/jp972692s .
Grgur, Branimir, Marković, NM, Ross, PN, "Electrooxidation of H-2, CO, and H-2/CO mixtures on a well-characterized Pt70Mo30 bulk alloy electrode" in Journal of Physical Chemistry B, 102, no. 14 (1998):2494-2501, https://doi.org/10.1021/jp972692s . .