Gallium Phosphide photoanode coated with TiO2 and CoOx for stable photoelectrochemical water oxidation

M. Alqahtani, S. Ben-Jabar, M. Ebaid, S. Sathasivam, P. Jurczak, X. Xia, A. Alromaeh, C. Blackman, Y. Qin, B. Zhang, Boon S. Ooi, H. Liu, I. P. Parkin, J. Wu

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5 Scopus citations

Abstract

Gallium Phosphide (GaP) has a band gap of 2.26 eV and a valance band edge that is more negative than the water oxidation level. Hence, it may be a promising material for photoelectrochemical water splitting. However, one thing GaP has in common with other III-V semiconductors is that it corrodes in photoelectrochemical reactions. Cobalt oxide (CoOx) is a chemically stable and highly active oxygen evolution reaction co-catalyst. In this study, we protected a GaP photoanode by using a 20 nm TiO2 as a protection layer and a 2 nm cobalt oxide co-catalyst layer, which were both deposited via atomic layer deposition (ALD). A GaP photoanode that was modified by CoOx exhibited much higher photocurrent, potential, and photon-to-current efficiency than a bare GaP photoanode under AM1.5G illumination. A photoanode that was coated with both TiO2 and CoOx layers was stable for over 24 h during constant reaction in 1 M NaOH (pH 13.7) solution under one sun illumination.
Original languageEnglish (US)
Pages (from-to)A364
JournalOptics Express
Volume27
Issue number8
DOIs
StatePublished - Mar 18 2019

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