Hybrid photoanodes for visible light-driven water oxidation: the beneficial and detrimental effects of nickel oxide cocatalyst
peer-reviewed
Erstveröffentlichung
2020-08-27Authors
Longchin, Pimchanok
Mitoraj, Dariusz
Reyes, Oliver Mendoza
Adler, Christiane
Wetchakun, Natda
Wissenschaftlicher Artikel
Published in
Journal of Physics: Energy ; 2 (2020), 4. - Art.-Nr. 044001. - eISSN 2515-7655
Link to original publication
https://dx.doi.org/10.1088/2515-7655/abaec9Faculties
Fakultät für NaturwissenschaftenInstitutions
Institut für ElektrochemieDocument version
published version (publisher's PDF)Abstract
AbstractHybrid photoanodes comprising polymer-based light absorbers coupled to oxygen-evolving cocatalysts represent a promising, yes still underdeveloped, approach to photoelectrochemical splitting of water into hydrogen and oxygen. In this study, we investigate nickel oxide (NiOx) nanoparticles as a water oxidation catalyst in hybrid photoanodes based on polymeric carbon nitride (CNx) supported on electron-collecting mesoporous TiO2 support. The performance of the resulting TiO2–CNx/NiOx photoanodes is evaluated with respect to our previous results on hybrid TiO2–CNx photoanodes modified with IrOx and CoO(OH)x cocatalysts. The deposition of NiOx into TiO2–CNx photoanodes enhances significantly the photocurrent (from <8 μA to >250 μA cm–2 at 1.23 V vs. RHE) under visible light irradiation (λ > 420 nm, ∼200 mW cm−2) and triggers the photoelectrocatalytic oxygen evolution. No oxygen evolution was observed without a cocatalyst. As compared to photoanodes modified with IrOx or CoO(OH)x, the TiO2–CNx/NiOx photoanodes excel by the very negative photocurrent onset potential (0 V vs. RHE), which we ascribe to good hole-extracting properties of NiOx. However, the comparatively low Faradaic efficiencies for oxygen evolution (∼18%) and dramatically decreased operational stability of the photoanodes indicate that the extracted holes do not efficiently oxidize water to dioxygen, but instead accumulate in the NiOx particles and increase thus the oxidative photodegradation of the photoanodes. Our study highlights the fact that employing outstanding electrocatalysts like NiOx in photoelectrochemical water-splitting systems does not necessarily lead to satisfactory results, especially when the photoelectrode cannot be operated at optimal pH due to light absorber stability issues.
DFG Project THU
TRR 234 Teilprojekt B06 / Molekular funktionalisierte Kohlenstoffnitrid-Polymere für die lichtgetriebene Wasserspaltung / DFG / 364549901
Is supplemented by
https://iopscience.iop.org/article/10.1088/2515-7655/abaec9#Subject headings
[GND]: Titandioxid | Fotoelektrochemie[LCSH]: Titanium dioxide | Photoelectrochemistry
[Free subject headings]: polymeric carbon nitride | water splitting | charge separation | oxygen evolution reaction
[DDC subject group]: DDC 540 / Chemistry & allied sciences
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Show full item recordDOI & citation
Please use this identifier to cite or link to this item: http://dx.doi.org/10.18725/OPARU-50320
Longchin, Pimchanok et al. (2023): Hybrid photoanodes for visible light-driven water oxidation: the beneficial and detrimental effects of nickel oxide cocatalyst. Open Access Repositorium der Universität Ulm und Technischen Hochschule Ulm. http://dx.doi.org/10.18725/OPARU-50320
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