Understanding oxygen evolution mechanisms by tracking charge flow at the atomic level

Changming Zhao; Hao Tian; Zhigang Zou; Hu Xu; Shuk-Yin Tong

doi:10.1016/j.isci.2023.107037

Understanding oxygen evolution mechanisms by tracking charge flow at the atomic level

iScience. 2023 Jun 8;26(7):107037. doi: 10.1016/j.isci.2023.107037. eCollection 2023 Jul 21.

Authors

Changming Zhao^{1

2}, Hao Tian^{1

3}, Zhigang Zou¹, Hu Xu², Shuk-Yin Tong^{1

2

4}

Affiliations

¹ School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen 518172, China.
² Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China.
³ University of Science and Technology of China, Chemistry and Material Science College, Hefei 230026, China.
⁴ Institute of Materials Science and Devices, Suzhou University of Science and Technology, Suzhou 215009, China.

Abstract

Current classifications of oxygen evolution catalysts are based on energy levels of the clean catalysts. It is generally asserted that a LOM-catalyst can only follow LOM chemistry in each electron transfer step and that there can be no mixing between AEM and LOM steps without an external trigger. We use ab initio theory to track the charge flow of the water-on-catalyst system and show that the position of water orbitals is pivotal in determining whether an electron transfer step is water dominated oxidation (WDO), lattice-oxygen dominated oxidation (LoDO), or metal dominated oxidation (MDO). Microscopic photo-catalytic pathways of TiO₂ (110), a material whose lattice oxygen bands lie above the metal bands, show that viable OER pathways follow either all AEM steps or mixed AEM-LOM steps. The results provide a correct description of redox chemistries at the atomic level and advance our understanding of how water-splitting catalysts produce desorbed oxygen.

Keywords: Molecular mechanics calculations; Physical chemistry; Theoretical chemistry.