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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Insights on Thickness-Dependent Charge Transfer Efficiency Modulated by Ultrasonic Treatment in Hematite Photoanodes

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Author(s):
Freitas, Andre L. M. [1, 2] ; Tofanello, Aryane [2] ; Souza, Flavio L. [3, 2] ; Li, Yat [1]
Total Authors: 4
Affiliation:
[1] Univ Calif Santa Cruz, Dept Chem & Biochem, Santa Cruz, CA 95064 - USA
[2] Univ Fed ABC UFABC, Lab Alternat Energy & Nanomat LEAN, BR-09210580 Santo Andre, SP - Brazil
[3] Brazilian Nanotechnol Natl Lab LNNano, BR-13083100 Campinas, SP - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Journal of Physical Chemistry C; v. 125, n. 18, p. 9981-9989, MAY 13 2021.
Web of Science Citations: 0
Abstract

The comprehension of the solid-liquid interface associated with the poor charge carrier dynamic of hematite has prevented its commercial application as a photoanode in a photoelectrochemical cell. The development of a low-cost and scalable strategy to overcome such drawbacks is still being pursued by the scientific community. Here, a simple surface modification of hematite photoanode designed with different thicknesses was carried out by employing an ultrasonic treatment (UST) process. UST creates an inhomogeneous defect distribution based on the solid-liquid energetics. The thicker photoanodes (H-4h) showed that the mechanical process can contribute to removing unstable layers, creating favorable sites for oxygen evolution without compromise the solid-solid interface. The UST approach for H-2h has promoted surface states pinning and possibly increased the stress between hematite and FTO. The effects on thinner photoanodes (H-2h) can drastically create polarized states that enhance surface trapping states, reducing the photogenerated charge lifetime. The outcome findings reveal that the surface hydroxylation might be extremely dependent on the electrode thickness. This study indicates that the UST approach is an efficient tool to boost the performance of thicker photoanodes, as desired for practical applications. Thus, for thinner layers, the stress induced at the hematite-FTO interface can be aggravated by mechanical treatment overcoming the beneficial effects at the solid-liquid interface. In fact, hydroxylation conducted via the sonication process is highly recommended for designing thicker films. (AU)

FAPESP's process: 17/11986-5 - Generation and storage of New Energy: bringing technological development for the country
Grantee:Ana Flávia Nogueira
Support Opportunities: Research Grants - Research Centers in Engineering Program
FAPESP's process: 14/11736-0 - Development of inorganic material nanostructures for conversion and storage of solar energy
Grantee:André Luiz Martins de Freitas
Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
FAPESP's process: 17/25935-3 - Understanding the charge transport at hematite photoelectrodes interfaces
Grantee:André Luiz Martins de Freitas
Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)