H2 Production from the Photocatalytic Reforming of Ethylene Glycol: Effect of TiO2 Crystalline Phase on Photo-Oxidation Mechanism

Luke Roebuck; Helen Daly; Lan Lan; Joseph Parker; Angus Gostick; Nathan Skillen; Sarah Haigh; Marta Falkowska; Chris Hardacre

doi:10.1016/j.jcat.2024.115876

H₂ Production from the Photocatalytic Reforming of Ethylene Glycol: Effect of TiO₂ Crystalline Phase on Photo-Oxidation Mechanism

Luke Roebuck, Helen Daly, Lan Lan, Joseph Parker, Angus Gostick, Nathan Skillen, Sarah Haigh, Marta Falkowska, Chris Hardacre

Research output: Contribution to journal › Article › peer-review

Abstract

In this work, the mechanism of H₂ production from ethylene glycol as a model compound for photoreforming over platinized TiO₂ is presented with particular focus on the effect of the TiO₂ polymorph. It was found that Pt/anatase and Pt/anatase:rutile (P25) had similar H₂ production activities and both catalysts followed an indirect oxidation pathway where ethylene glycol was oxidised via hydroxyl radicals to glycolaldehyde. In contrast, Pt/rutile primarily oxidised ethylene glycol directly into formaldehyde. The formaldehyde was unable to react further, which significantly reduced the formation of hydrogen despite similar conversion of ethylene glycol compared with the other supports used. We propose that these differences are due to different adsorption behaviour and hole transfer mechanism on the different TiO₂ crystalline phases. In particular, ethylene glycol complexation on Ti_5c sites on the dominant (110) facet of rutile leads to a direct hole transfer and an oxidative C-C cleavage mechanism prevailing.

Original language	English
Article number	1351-0711
Journal	Journal of Catalysis
Volume	442
Early online date	28 Nov 2024
DOIs	https://doi.org/10.1016/j.jcat.2024.115876 https://doi.org/10.1016/j.jcat.2024.115876
Publication status	Published - 1 Feb 2025

Keywords

ethylene glycol
Photocatalysis
photoreforming
TiO2
oxidation mechanism
Hydrogen production

Research Beacons, Institutes and Platforms

National Graphene Institute

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Roebuck, L., Daly, H., Lan, L., Parker, J., Gostick, A., Skillen, N., Haigh, S., Falkowska, M., & Hardacre, C. (2025). H₂ Production from the Photocatalytic Reforming of Ethylene Glycol: Effect of TiO₂ Crystalline Phase on Photo-Oxidation Mechanism. Journal of Catalysis , 442, Article 1351-0711. https://doi.org/10.1016/j.jcat.2024.115876, https://doi.org/10.1016/j.jcat.2024.115876

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abstract = "In this work, the mechanism of H2 production from ethylene glycol as a model compound for photoreforming over platinized TiO2 is presented with particular focus on the effect of the TiO2 polymorph. It was found that Pt/anatase and Pt/anatase:rutile (P25) had similar H2 production activities and both catalysts followed an indirect oxidation pathway where ethylene glycol was oxidised via hydroxyl radicals to glycolaldehyde. In contrast, Pt/rutile primarily oxidised ethylene glycol directly into formaldehyde. The formaldehyde was unable to react further, which significantly reduced the formation of hydrogen despite similar conversion of ethylene glycol compared with the other supports used. We propose that these differences are due to different adsorption behaviour and hole transfer mechanism on the different TiO2 crystalline phases. In particular, ethylene glycol complexation on Ti5c sites on the dominant (110) facet of rutile leads to a direct hole transfer and an oxidative C-C cleavage mechanism prevailing.",

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Roebuck, L, Daly, H, Lan, L, Parker, J, Gostick, A, Skillen, N, Haigh, S , Falkowska, M & Hardacre, C 2025, 'H₂ Production from the Photocatalytic Reforming of Ethylene Glycol: Effect of TiO₂ Crystalline Phase on Photo-Oxidation Mechanism', Journal of Catalysis , vol. 442, 1351-0711. https://doi.org/10.1016/j.jcat.2024.115876, https://doi.org/10.1016/j.jcat.2024.115876

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T1 - H2 Production from the Photocatalytic Reforming of Ethylene Glycol: Effect of TiO2 Crystalline Phase on Photo-Oxidation Mechanism

AU - Roebuck, Luke

AU - Daly, Helen

AU - Lan, Lan

AU - Parker, Joseph

AU - Gostick, Angus

AU - Skillen, Nathan

AU - Haigh, Sarah

AU - Falkowska, Marta

AU - Hardacre, Chris

PY - 2025/2/1

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N2 - In this work, the mechanism of H2 production from ethylene glycol as a model compound for photoreforming over platinized TiO2 is presented with particular focus on the effect of the TiO2 polymorph. It was found that Pt/anatase and Pt/anatase:rutile (P25) had similar H2 production activities and both catalysts followed an indirect oxidation pathway where ethylene glycol was oxidised via hydroxyl radicals to glycolaldehyde. In contrast, Pt/rutile primarily oxidised ethylene glycol directly into formaldehyde. The formaldehyde was unable to react further, which significantly reduced the formation of hydrogen despite similar conversion of ethylene glycol compared with the other supports used. We propose that these differences are due to different adsorption behaviour and hole transfer mechanism on the different TiO2 crystalline phases. In particular, ethylene glycol complexation on Ti5c sites on the dominant (110) facet of rutile leads to a direct hole transfer and an oxidative C-C cleavage mechanism prevailing.

AB - In this work, the mechanism of H2 production from ethylene glycol as a model compound for photoreforming over platinized TiO2 is presented with particular focus on the effect of the TiO2 polymorph. It was found that Pt/anatase and Pt/anatase:rutile (P25) had similar H2 production activities and both catalysts followed an indirect oxidation pathway where ethylene glycol was oxidised via hydroxyl radicals to glycolaldehyde. In contrast, Pt/rutile primarily oxidised ethylene glycol directly into formaldehyde. The formaldehyde was unable to react further, which significantly reduced the formation of hydrogen despite similar conversion of ethylene glycol compared with the other supports used. We propose that these differences are due to different adsorption behaviour and hole transfer mechanism on the different TiO2 crystalline phases. In particular, ethylene glycol complexation on Ti5c sites on the dominant (110) facet of rutile leads to a direct hole transfer and an oxidative C-C cleavage mechanism prevailing.

KW - ethylene glycol

KW - Photocatalysis

KW - photoreforming

KW - TiO2

KW - oxidation mechanism

KW - Hydrogen production

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