期刊
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
卷 2, 期 6, 页码 572-576出版社
AMER CHEMICAL SOC
DOI: 10.1021/jz101753e
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资金
- Ford Motor Company
- DOE [DE-AC02-06CH11357]
We report the reaction pathways and barriers for the oxygen reduction reaction (ORR) on platinum, both for gas phase and in solution, based on quantum mechanics calculations (PBE-DFT) on semi-infinite slabs. We find a new mechanism in solution: O-2 -> 2O(ad) (E-act = 0.00 eV), O-ad + H2Oad -> 2OH(ad) (E-act = 0.50 eV), OHad + H-ad -> H2Oad (E-act = 0.24 eV), in which OHad is formed by the hydration of surface O-ad. For the gas phase (hydrophilic phase of Nafion), we find that. the favored step for activation of the O-2 is H-ad + O-2ad -> HOOad (E-act = 0.30 eV) -> HOad + O-ad (E-act = 0.12 eV) followed by O-ad + H2Oad -> 2OH(ad) (E-act = 0.23 eV), OHad + H-ad -> H2Oad (E-act = 0.14 eV). This suggests that to improve the efficiency of ORR catalysts, we should focus on decreasing the barrier for O-ad hydration while providing hydrophobic conditions for the OH and H2O formation steps.
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