Journal
ACS CATALYSIS
Volume 12, Issue 2, Pages 1201-1208Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acscatal.1c04910
Keywords
anatase nanotubes; SECCM; charge separation; PEC water splitting; space charge layer; oxygen evolution; active site visualization
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Funding
- PRESTO from the Japan Science and Technology Agency (JST) [JPMJPR18T1, JPMJPR18T8]
- Japan Society for the Promotion of Science (JSPS) [19H00915, 20H02525, 15H05422, 15K13263, 20K21141, 16H00885]
- World Premier International Research Center Initiative (WPI), MEXT, Japan
- Asahi Glass Foundation
- Hokuriku Bank
- Murata Science Foundation
- Russian Science Foundation [19-19-00626]
- Grants-in-Aid for Scientific Research [16H00885, 15K13263, 19H00915, 20H02525, 20K21141] Funding Source: KAKEN
- Russian Science Foundation [19-19-00626] Funding Source: Russian Science Foundation
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The photoelectrochemical (PEC) catalytic effects of anatase TiO2-nanotube arrays grown on Ti felt are explored using scanning electrochemical cell microscopy (SECCM). The results support the transport of photoexcited electrons along the TiO2 nanotubes and the model of orthogonal electron-hole separation.
Photoelectrochemical (PEC) water splitting is an important and rapidly developing technology that produces H-2 as a renewable resource, but local surface investigations remain a major challenge. Using scanning electrochemical cell microscopy (SECCM), the PEC catalytic effects of anatase TiO2-nanotube arrays grown on Ti felt are explored. The SECCM imaging is performed both perpendicular and parallel to the nanotube growth direction. In contrast to bulk cyclic voltammetry measurements, SECCM measures only the upper region of the nanotubes that remain in contact with the electrolyte, which provides a better understanding of the phenomena connected to the longitudinal charge transport. Despite the presence of regions with higher and lower photocurrent, the PEC reactivities of the nanotube tops and walls are roughly comparable with each other. The data support the model of orthogonal electron-hole separation. This model facilitates the photogenerated hole diffusion over the short distance to the electrolyte interface due to the sufficient transport of photoexcited electrons along the long axial direction of TiO2 nanotubes and is often applied to one-dimensional systems. Observed results were additionally supported by the nanotube decoration with photoelectrochemically deposited PbO2 particles.
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