The role of noncovalent interactions in electrocatalysis : trends in fuel cell reactions on Pt in alkaline solutions.
The classic models of metal electrode-electrolyte interfaces generally focus on either covalent interactions between adsorbates and solid surfaces or on long-range electrolyte-metal electrostatic interactions. Here we demonstrate that these traditional models are insufficient. To understand electrocatalytic trends in the oxygen reduction reaction (ORR), the hydrogen oxidation reaction (HOR) and the oxidation of methanol on platinum surfaces in alkaline electrolytes, non-covalent interactions must be considered. We find that non-covalent interactions between hydrated alkali metal cations M{sup +}(H{sub 2}O){sub x} and adsorbed OH (OH{sub ad}) species increase in the same order as the hydration energies of the corresponding cations (Li{sup +} >> Na{sup +} > K{sup +} > Cs{sup +}) and also correspond to an increase in the concentration of OH{sub ad}-M{sup +}(H{sub 2}O){sub x} clusters at the interface. These trends are inversely proportional to the activities of the ORR, the HOR and the oxidation of methanol on platinum (Cs{sup +} > K{sup +} > Na{sup +} >> Li{sup +}), which suggests that the clusters block the platinum active sites for electrocatalytic reactions.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); Toyota Central R&D Labs, Inc.
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 965250
- Report Number(s):
- ANL/MSD/JA-64667; TRN: US200919%%500
- Journal Information:
- Nat. Chem., Vol. 1, Issue 2009
- Country of Publication:
- United States
- Language:
- ENGLISH
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