First-principles studies of imidazolium chloroaluminate ionic liquids with different substitutions on the Pt(111) surface

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 635; p. 128079
• Main Authors: Du, Huanhuan, Tian, Guocai
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.02.2022
• Subjects: Ab initio; adsorption; Ionic liquid; Pt surface; Substituent; Ab initio; adsorption; Substituent; Pt surface; Ionic liquid
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2021.128079

The electrolyte/electrode interface is vital for aluminum electrodeposition, and is directly linked by the slight change of an imidazolium cation. The effect of functional groups substitution on the reactivity and adsorption behavior of methyl-imidazole heptachloride aluminum ILs such as 1-hydrogen-3-methylimidazole heptachloride aluminum ([H1MIM]Al2Cl7), 1-allyl-3-methylimidazole heptachloride aluminum ([AMIM]Al2Cl7), 1-Propyl-3-methylimidazole heptachloride aluminum (C3MIMAl2Cl7) and 1-methoxyethyl-3-methylimidazole heptachloride aluminum (MoeMIMAl2Cl7) on the Pt(111) surface were revealed by first-principles methods. The active centers of [H1MIM]Al2Cl7 and C3MIMAl2Cl7are distributed on the imidazole ring and the Cl atoms of the anion, while the active centers of [AMIM]Al2Cl7 andMoeMIMAl2Cl7 are distributed on the imidazole ring, the C or O atoms in the alkyl chain, and the Cl atoms of the anion. Moreover, the imidazole ring of [AMIM]Al2Cl7 has the minimum surface maximum value of electrostatic potential. It suggested that the imidazolium rings of these four ionic liquids (ILs) tend to adsorb on the Pt(111) surface in a flat-lying orientation, and that [AMIM]Al2Cl7more easily adsorbs on the surface. The distances between the Cl atoms of Al2Cl7- and the Pt(111) surface decrease, indicating that the Al2Cl7- of [AMIM]Al2Cl7 can easily penetrate the electric double layer and move to the cathode surface to be discharged, which speeds up the nucleation rate. Additionally, [C3MIM]+,[AMIM]+, and [MoeMIM]+have stronger interaction with the surfaces and larger volumes than [H1MIM]+, causing them to flatten the electrode surface and refine the grains during aluminum deposition. The results of adsorption calculations are found to be consistent with both the previous predictions and the experimental deposition effect of [AMIM]Al2Cl7and [H1MIM]Al2Cl7 on the Pt electrode. [Display omitted] •The structure and adsorption properties of four imidazolium chloroaluminate on the Pt(111) surface are revealed.•The introduction of alkenyl, propyl and ether to imidazole ring enhances the interaction and adsorption between ILs with Pt (111).•The increase of cation volume and adsorption of ILs with Pt(111) can refine the grain of aluminum deposits.