| Autor: |
Warburton RE; Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States., Mayer JM; Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States., Hammes-Schiffer S; Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States. |
| Abstrakt: |
Proton-coupled electron transfer (PCET) reactions on metal oxides require coupling between proton transfer at the solid-liquid interface and electron transfer involving defects at or near the band edge. Herein, hybrid functional periodic density functional theory is used to elucidate the impact of proton-coupled defects on the bond dissociation free energies (BDFEs) of O-H bonds on anatase TiO 2 surfaces. These O-H BDFEs are directly related to interfacial PCET thermochemistry. Comparison between geometrically similar O-H bonds associated with different defect types, namely conduction d-band electrons or valence p-band holes, reveals that the BDFEs differ by ∼81 kcal/mol (3.50 eV), comparable to the wide TiO 2 band gap. These differences are shown to be determined primarily by differences in electron transfer driving forces, which are analyzed by using band energies and inner-sphere reorganization energies within a Marcus theory framework. These fundamental insights about the impact of proton-coupled defects on PCET thermochemistry at semiconductor surfaces have broad implications for electrocatalysis. |
