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In situ XPS of competitive CO2/H2O absorption in an ionic liquid

Cole, Jordan ; Henderson, Zoë ; Thomas, Andrew G. ; Castle, Christopher ; Greer, Adam J. ; Hardacre, Christopher ; Scardamaglia, Mattia LU ; Shavorskiy, Andrey LU and Syres, Karen L. (2023) In JPhys Materials 6(4).
Abstract

Superbasic ionic liquids (SBILs) are being investigated as potential carbon dioxide (CO2) gas capture agents, however, the presence of H2O in the flue stream can inhibit the uptake of CO2. In this study a thin film of the SBIL trihexyltetradecylphosphonium 1,2,4-triazolide ([P66614][124Triz]) was deposited onto rutile TiO2 (110) using in situ electrospray deposition and studied upon exposure to CO2 and H2O using in situ near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS). The molar uptake ratio of gas in the electrosprayed SBIL (n gas :n IL) was calculated to be 0.3:1 for CO2, 0.7:1 for H2O, and 0.9:1 for... (More)

Superbasic ionic liquids (SBILs) are being investigated as potential carbon dioxide (CO2) gas capture agents, however, the presence of H2O in the flue stream can inhibit the uptake of CO2. In this study a thin film of the SBIL trihexyltetradecylphosphonium 1,2,4-triazolide ([P66614][124Triz]) was deposited onto rutile TiO2 (110) using in situ electrospray deposition and studied upon exposure to CO2 and H2O using in situ near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS). The molar uptake ratio of gas in the electrosprayed SBIL (n gas :n IL) was calculated to be 0.3:1 for CO2, 0.7:1 for H2O, and 0.9:1 for a CO2/H2O mixture. NAP-XPS taken at two different depths reveals that the competitive absorption of CO2 and H2O in [P66614][124Triz] varies with sampling depth. A greater concentration of CO2 absorbs in the bulk layers, while more H2O adsorbs/absorbs at the surface. The presence of H2O in the gas mixture does not inhibit the absorption of CO2. Measurements taken during exposure and after the removal of gas indicate that CO2 absorbed in the bulk does so reversibly, whilst CO2 adsorbed/absorbed at the surface does so irreversibly. This is contrary to the fully reversible CO2 reaction shown for bulk ionic liquids (ILs) in literature and suggests that irreversible absorption of CO2 in our highly-structured thin films is largely attributed to reactions at the surface. This has potential implications on IL gas capture and thin film IL catalysis applications.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
carbon capture, electrospray, ionic liquids, thin films, x-ray photoelectron spectroscopy
in
JPhys Materials
volume
6
issue
4
article number
045012
publisher
IOP Publishing
external identifiers
  • scopus:85182276793
ISSN
2515-7639
DOI
10.1088/2515-7639/acfdcf
language
English
LU publication?
yes
id
07940e2f-09c0-453d-9bac-c43288695b42
date added to LUP
2024-02-13 15:09:27
date last changed
2024-02-13 15:09:27
@article{07940e2f-09c0-453d-9bac-c43288695b42,
  abstract     = {{<p>Superbasic ionic liquids (SBILs) are being investigated as potential carbon dioxide (CO<sub>2</sub>) gas capture agents, however, the presence of H<sub>2</sub>O in the flue stream can inhibit the uptake of CO<sub>2</sub>. In this study a thin film of the SBIL trihexyltetradecylphosphonium 1,2,4-triazolide ([P<sub>66614</sub>][124Triz]) was deposited onto rutile TiO<sub>2</sub> (110) using in situ electrospray deposition and studied upon exposure to CO<sub>2</sub> and H<sub>2</sub>O using in situ near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS). The molar uptake ratio of gas in the electrosprayed SBIL (n <sub>gas</sub> :n <sub>IL</sub>) was calculated to be 0.3:1 for CO<sub>2</sub>, 0.7:1 for H<sub>2</sub>O, and 0.9:1 for a CO<sub>2</sub>/H<sub>2</sub>O mixture. NAP-XPS taken at two different depths reveals that the competitive absorption of CO<sub>2</sub> and H<sub>2</sub>O in [P<sub>66614</sub>][124Triz] varies with sampling depth. A greater concentration of CO<sub>2</sub> absorbs in the bulk layers, while more H<sub>2</sub>O adsorbs/absorbs at the surface. The presence of H<sub>2</sub>O in the gas mixture does not inhibit the absorption of CO<sub>2</sub>. Measurements taken during exposure and after the removal of gas indicate that CO<sub>2</sub> absorbed in the bulk does so reversibly, whilst CO<sub>2</sub> adsorbed/absorbed at the surface does so irreversibly. This is contrary to the fully reversible CO<sub>2</sub> reaction shown for bulk ionic liquids (ILs) in literature and suggests that irreversible absorption of CO<sub>2</sub> in our highly-structured thin films is largely attributed to reactions at the surface. This has potential implications on IL gas capture and thin film IL catalysis applications.</p>}},
  author       = {{Cole, Jordan and Henderson, Zoë and Thomas, Andrew G. and Castle, Christopher and Greer, Adam J. and Hardacre, Christopher and Scardamaglia, Mattia and Shavorskiy, Andrey and Syres, Karen L.}},
  issn         = {{2515-7639}},
  keywords     = {{carbon capture; electrospray; ionic liquids; thin films; x-ray photoelectron spectroscopy}},
  language     = {{eng}},
  number       = {{4}},
  publisher    = {{IOP Publishing}},
  series       = {{JPhys Materials}},
  title        = {{In situ XPS of competitive CO<sub>2</sub>/H<sub>2</sub>O absorption in an ionic liquid}},
  url          = {{http://dx.doi.org/10.1088/2515-7639/acfdcf}},
  doi          = {{10.1088/2515-7639/acfdcf}},
  volume       = {{6}},
  year         = {{2023}},
}