Here, we report a detailed mechanistic study of the oxygen reduction reaction (ORR) on Pt(111) in alkaline solution, combining density functional theory and kinetic Monte Carlo simulations. A complex reaction network including four possible pathways via either 2e– or 4e– transfer is established and is able to reproduce the experimental measured polarization curve at both low- and high-potential regions. Our results show that it is essential to account for solvation by water and the dynamic coverage of *OH to describe the reaction kinetics well. In addition, a chemisorbed water (*H2O)-mediated mechanism including 4e– transfers is identified, where the reduction steps via *H2O on the surface are potential-independent and only the final removal of *OH from the surface in the form of OH–(aq) contributes to the current. For the ORR in alkaline solutions, such a mechanism is more competitive than the associative and dissociative mechanisms typically used to describe the ORR in acid solution. Finally, *OH and **O2 intermediates are found to be critically important for tuning the ORR activity of Pt in alkaline solution. To enhance the activity, the binding of Pt should be tuned in such a way that *OH binding is weak enough to release more surface sites under working conditions, while **O2 binding is strong enough to enable the ORR via the 4e– transfer mechanism.
Liu, Shizhong, et al. "Mechanism of oxygen reduction reaction on Pt(111) in alkaline solution: Importance of chemisorbed water on surface." Journal of Physical Chemistry. C, vol. 120, no. 28, Jun. 2016. https://doi.org/10.1021/acs.jpcc.6b05126
Liu, Shizhong, White, Michael G., & Liu, Ping (2016). Mechanism of oxygen reduction reaction on Pt(111) in alkaline solution: Importance of chemisorbed water on surface. Journal of Physical Chemistry. C, 120(28). https://doi.org/10.1021/acs.jpcc.6b05126
Liu, Shizhong, White, Michael G., and Liu, Ping, "Mechanism of oxygen reduction reaction on Pt(111) in alkaline solution: Importance of chemisorbed water on surface," Journal of Physical Chemistry. C 120, no. 28 (2016), https://doi.org/10.1021/acs.jpcc.6b05126
@article{osti_1328388,
author = {Liu, Shizhong and White, Michael G. and Liu, Ping},
title = {Mechanism of oxygen reduction reaction on Pt(111) in alkaline solution: Importance of chemisorbed water on surface},
annote = {Here, we report a detailed mechanistic study of the oxygen reduction reaction (ORR) on Pt(111) in alkaline solution, combining density functional theory and kinetic Monte Carlo simulations. A complex reaction network including four possible pathways via either 2e– or 4e– transfer is established and is able to reproduce the experimental measured polarization curve at both low- and high-potential regions. Our results show that it is essential to account for solvation by water and the dynamic coverage of *OH to describe the reaction kinetics well. In addition, a chemisorbed water (*H2O)-mediated mechanism including 4e– transfers is identified, where the reduction steps via *H2O on the surface are potential-independent and only the final removal of *OH from the surface in the form of OH–(aq) contributes to the current. For the ORR in alkaline solutions, such a mechanism is more competitive than the associative and dissociative mechanisms typically used to describe the ORR in acid solution. Finally, *OH and **O2 intermediates are found to be critically important for tuning the ORR activity of Pt in alkaline solution. To enhance the activity, the binding of Pt should be tuned in such a way that *OH binding is weak enough to release more surface sites under working conditions, while **O2 binding is strong enough to enable the ORR via the 4e– transfer mechanism.},
doi = {10.1021/acs.jpcc.6b05126},
url = {https://www.osti.gov/biblio/1328388},
journal = {Journal of Physical Chemistry. C},
issn = {ISSN 1932-7447},
number = {28},
volume = {120},
place = {United States},
publisher = {American Chemical Society},
year = {2016},
month = {06}}
Brookhaven National Laboratory (BNL), Upton, NY (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI ID:
1328388
Report Number(s):
BNL--112715-2016-JA; KC0301020
Journal Information:
Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 28 Vol. 120; ISSN 1932-7447