| Autor: |
Kuo DY; Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States., Lu X; Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States., Hu B; Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States., Abruña HD; Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States.; Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States., Suntivich J; Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States.; Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States. |
| Abstrakt: |
The formation of surface-bound hydrogen from one proton and one electron plays an enabling role in renewable hydrogen production. Quantifying the surface-bound hydrogen formation, however, requires decoupling the delicate interplay of numerous processes. We study cyclic voltammetry (CV) at fast scan rates to characterize the rate constant for the surface-bound hydrogen formation (also known as underpotential deposition hydrogen, UPD H ad ). We find that the formation of H ad on Pt(111) single crystals is ∼100× faster in acid than in base. Reaction-order analysis indicates that the formation of H ad occurs as a standard proton-coupled electron transfer (PCET) reaction in acid, whereas in base, it displays a pH-independent rate constant, indicating the presence of a chemical step such as the reorganization of interfacial water. Our results provide a methodology for quantifying the interfacial PCET kinetics and reveal the mechanistic nature of the UPD H ad formation as the reason the hydrogen evolution electrocatalysis on Pt is faster in acid than in base. |
