Aligning Electronic and Protonic Energy Levels of Proton-Coupled Electron Transfer in Water Oxidation on Aqueous TiO2

Jun Cheng, Xiandong Liu, John A Kattirtzi, Joost VandeVondele, Michiel Sprik

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

The high overpotential in water oxidation on anodes is a limiting factor for the large-scale application of photoelectrochemical cells. To overcome this limitation, it is essential to understand the four proton-coupled electron transfer (PCET) steps in the reaction mechanism and their implications to the overpotential. Herein, a simple scheme to compute the energies of the PCET steps in water oxidation on the aqueous TiO2 surface using a hybrid density functional is described. An energy level diagram for fully decoupled electron- and proton-transfer reactions in which both electronic and protonic levels are placed on the same potential scale is also described. The level diagram helps to visualize the electronic and protonic components of the overpotential, and points out what are needed to improve. For TiO2 , it is found that its catalytic activity is due to aligning the protonic energy levels in the PCET steps, while improving the activity requires also aligning the electronic levels.

Original languageEnglish
Pages (from-to)12046-12050
Number of pages5
JournalAngewandte Chemie International Edition
Volume53
Issue number45
Early online date23 Jul 2014
DOIs
Publication statusPublished - 3 Nov 2014

Keywords

  • computational chemistry
  • heterogenous catalysis
  • photochemistry
  • proton transfer
  • thermodynamics

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