Characterization of Interfacial Charge-Transfer Photoexcitation of Polychromium-Oxo-Electrodeposited TiO2 as an Earth-Abundant Photoanode for Water Oxidation Driven by Visible Light

Debraj Chandra; Ryougen Tsuriya; Tsubasa Sato; Daisuke Takama; Naoto Abe; Masashi Kajita; Dong Li; Takanari Togashi; Masato Kurihara; Kenji Saito; Tatsuto Yui; Masayuki Yagi

doi:10.1002/cplu.201600288

Characterization of Interfacial Charge-Transfer Photoexcitation of Polychromium-Oxo-Electrodeposited TiO₂ as an Earth-Abundant Photoanode for Water Oxidation Driven by Visible Light

Chempluschem. 2016 Oct;81(10):1116-1122. doi: 10.1002/cplu.201600288.

Authors

Affiliations

¹ Department of Materials Science and Technology, Faculty of Engineering, Niigata University, 8050 Ikarashi-2, Niigata, 950-2181, Japan.
² Department of Material and Biological Chemistry, Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata, 990-8560, Japan.

PMID: 31964075
DOI: 10.1002/cplu.201600288

Abstract

Polychromium-oxo-deposited TiO₂ (Cr^III _x O_y /TiO₂ ) electrodes were fabricated by a simple electrochemical technique by using different TiO₂ basal electrodes (anatase, rutile, and mixed polymorphic phases P25) as earth-abundant photoanodes for visible-light-driven water oxidation. The high-resolution transmission electron microscopy (HR-TEM) observation illustrated that an Cr^III _x O_y layer with approximately 2-3 nm thickness was formed on the surface of the crystalline TiO₂ particles. Upon visible-light irradiation of the electrodes, the photoanodic current based on water oxidation was generated at the Cr^III _x O_y /TiO₂ electrodes. However, the wavelength (below 620 nm) for photocurrent generation at Cr^III _x O_y /TiO₂ -rutile was longer than that (below 560 nm) at Cr^III _x O_y /TiO₂ -P25 by 60 nm, which is in agreement with the difference (0.2 eV) in the conduction band (CB) edge energy between rutile and anatase TiO₂ . This gives a quantitative account for the photocurrent generation based on interfacial charge transfer (IFCT) from Cr 3d of the deposited Cr^III _x O_y layer to the TiO₂ CB. The photocurrent generated for Cr^III _x O_y /TiO₂ -rutile was higher than that for Cr^III _x O_y /TiO₂ -anatase, which is ascribed to 1) more effective Cr^III _x O_y deposition on the rutile particles, 2) a larger electrolyte/Cr^III _x O_y interface for water oxidation as a result of smaller rutile particles (ca. 30-40 nm) compared with larger P25 particles (ca. 40-80 nm), and 3) more effective use of visible light owing to the low energy IFCT transition of rutile.

Keywords: TiO2 photoanodes; artificial photosynthesis; interfacial charge transfer; water oxidation; water splitting.

Abstract

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