ChemRxiv
These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
template nolink.pdf (975.86 kB)

Identifying the Spectroelectrochemical Characteristics of Hematite Photoanodes for Water Oxidation

preprint
submitted on 29.04.2021, 07:45 and posted on 29.04.2021, 13:18 by Jifang Zhang, Qiyuan Lin, Zhenlei Wang, Haowen Liu, Yuegang Zhang
Achieving efficient solar water splitting using hematite (α-Fe2O3), one of the most promising candidates for photoanodes, requires photogenerated holes to be efficiently used for water oxidation. However, this goal is obstructed by multiple undesirable recombination processes, as well as insufficient fundamental mechanistic understandings of water oxidation kinetics, particularly as to the nature of reaction pathways and possible reaction intermediates. Here we spectroelectro-chemically identify some of the most critical interfacial processes which determine the photoelectrocatalytic efficiencies of water oxidation, for hematite films with varied surface properties by tailoring the doping level of titanium. The spectroscopic signals of the processes inactive for water oxidation, including oxidation of intra-gap Fe2+ states and Fermi level pinning, are successfully distinguished from that of the active reaction intermediate, Fe(IV)=O. In addition, our kinetic analyses reveal two water oxidation pathways, of which the direct hole transfer mechanism becomes dominant over the surface states-mediated mechanism when the hematite surface is reconstructed by high levels of titanium dopants.

Funding

China postdoctoral science foundation (No. 2019TQ0175)

National Natural Science Foun-dation of China (No. U1832218)

History

Email Address of Submitting Author

j_zhang@mail.tsinghua.edu.cn

Institution

Tsinghua University

Country

China

ORCID For Submitting Author

0000-0003-1843-4686

Declaration of Conflict of Interest

The authors declare no conflict of interest.

Version Notes

28 April 2021

Exports