Abstract
In this study, X-ray photoelectron spectroscopy is used to analyse nine morpholinium ionic liquids, which are of great interest in green chemistry because of their low toxicity and high recyclability. The effect of the alkyl chain length on the aliphatic C 1s binding energy and the impact of the anion basicity on the cationic N 1s and O 1s binding energies are investigated. It is concluded that by changing the basicity of the anion, there is a more notable change in the electronic environment of the oxygen centre. The impact of a long alkyl side substituent on the cation-anion interactions is also discussed. It is observed that there is an intense charge shielding effect of the alkyl side chain in the cases of octyl and dodecyl substituents, which is reflected in the reduced Br 3d5/2 binding energy.
| Original language | English |
|---|---|
| Pages (from-to) | 24845-24851 |
| Number of pages | 7 |
| Journal | Physical Chemistry Chemical Physics |
| Volume | 24 |
| Issue number | 40 |
| DOIs | |
| State | Published - Sep 16 2022 |
Funding
S. M is grateful to the China Scholarship Council for the grant of a scholarship under the State Scholarship Fund (201808210439) as a Visiting Scholar at Oak Ridge National Laboratory (ORNL). PL thanks the University of Nottingham and EPSRC (EP/V037943/1, EP/V000055/1 and EP/S022236/1) for support. All ionic liquids were prepared by Dr Sheng Dai's group at ORNL. Dr Chi-Linh Do-Thanh from the University of Tennessee (Knoxville) is acknowledged for NMR characterisation. Dr Harry Meyer III from ORNL is acknowledged for XPS training and technical discussions. The characterisation work was in part supported by the Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE) (DE-AC05-00OR22725) and performed at ORNL's Materials Characterisation Core.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | DE-AC05-00OR22725 |
| Office of Energy Efficiency and Renewable Energy | |
| Oak Ridge National Laboratory | |
| University of Tennessee | |
| Engineering and Physical Sciences Research Council | EP/S022236/1, EP/V037943/1, EP/V000055/1 |
| University of Nottingham | |
| China Scholarship Council | 201808210439 |