Understanding oxygen evolution mechanisms by tracking charge flow at the atomic level
Changming Zhao,
Hao Tian,
Zhigang Zou,
Hu Xu,
Shuk-Yin Tong
Affiliations
Changming Zhao
School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen 518172, China; Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
Hao Tian
School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen 518172, China; University of Science and Technology of China, Chemistry and Material Science College, Hefei 230026, China
Zhigang Zou
School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen 518172, China
Hu Xu
Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China; Corresponding author
Shuk-Yin Tong
School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen 518172, China; Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China; Institute of Materials Science and Devices, Suzhou University of Science and Technology, Suzhou 215009, China; Corresponding author
Summary: 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.
