Understanding the Roles of Oxygen Vacancies in Hematite-Based Photoelectrochemical Processes

Zhiliang Wang; Xin Mao; Peng Chen; Mu Xiao; Sabiha Akter Monny; Songcan Wang; Muxina Konarova; Aijun Du; Lianzhou Wang

doi:10.1002/anie.201810583

Understanding the Roles of Oxygen Vacancies in Hematite-Based Photoelectrochemical Processes

Angew Chem Int Ed Engl. 2019 Jan 21;58(4):1030-1034. doi: 10.1002/anie.201810583. Epub 2018 Dec 18.

Authors

Zhiliang Wang¹, Xin Mao², Peng Chen¹, Mu Xiao¹, Sabiha Akter Monny¹, Songcan Wang¹, Muxina Konarova¹, Aijun Du², Lianzhou Wang¹

Affiliations

¹ Nanomaterials Centre, School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, QLD, 4072, Australia.
² School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Gardens Point Campus, Brisbane, QLD, 4001, Australia.

PMID: 30417505
DOI: 10.1002/anie.201810583

Abstract

Oxygen vacancy (V_O ) engineering is an effective method to tune the photoelectrochemical (PEC) performance, but the influence of V_O on photoelectrodes is not well understood. Using hematite as a prototype, we herein report that V_O functions in a more complicated way in PEC process than previously reported. Through a comprehensive analysis of the key charge transfer and surface reaction steps in PEC processes on a hematite photoanode, we clarify that V_O can facilitate surface electrocatalytic processes while leading to severe interfacial recombination at the semiconductor/electrolyte (S-E) interface, in addition to the well-reported improvements in bulk conductivity. The improved bulk conductivity and surface catalysis are beneficial for bulk charge transfer and surface charge consumption while interfacial charge transfer deteriorates because of recombination through V_O -induced trap states at the S-E interface.

Keywords: charge recombination; charge transfer; interfaces; oxygen vacancies; surface reactions.