Effect of water on the electroresponsive structuring and friction in dilute and concentrated ionic liquid lubricant mixturesShow others and affiliations
2020 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 22, no 48, p. 28191-28201Article in journal (Refereed) Published
Abstract [en]
The effect of water on the electroactive structuring of a tribologically relevant ionic liquid (IL) when dispersed in a polar solvent has been investigated at a gold electrode interface using neutron reflectivity (NR). For all solutions studied, the addition of small amounts of water led to clear changes in electroactive structuring of the IL at the electrode interface, which was largely determined by the bulk IL concentration. At a dilute IL concentration, the presence of water gave rise to a swollen interfacial structuring, which exhibited a greater degree of electroresponsivity with applied potential compared to an equivalent dry solution. Conversely, for a concentrated IL solution, the presence of water led to an overall thinning of the interfacial region and a crowding-like structuring, within which the composition of the inner layer IL layers varied systematically with applied potential. Complementary nanotribotronic atomic force microscopy (AFM) measurements performed for the same IL concentration, in dry and ambient conditions, show that the presence of water reduces the lubricity of the IL boundary layers. However, consistent with the observed changes in the IL layers observed by NR, reversible and systematic control of the friction coefficient with applied potential was still achievable. Combined, these measurements provide valuable insight into the implications of water on the interfacial properties of ILs at electrified interfaces, which inevitably will determine their applicability in tribotronic and electrochemical contexts.
Place, publisher, year, edition, pages
Royal Society of Chemistry , 2020. Vol. 22, no 48, p. 28191-28201
Keywords [en]
Atomic force microscopy, Boundary layers, Electrodes, Friction, Ionic liquids, Ambient conditions, Applied potentials, Electrified interface, Electrode interface, Friction coefficients, Interfacial property, Neutron reflectivity, Systematic control, Phase interfaces
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:ri:diva-51936DOI: 10.1039/d0cp05110aScopus ID: 2-s2.0-85098937782OAI: oai:DiVA.org:ri-51936DiVA, id: diva2:1519864
Note
Funding details: Vetenskapsrådet, VR, 2018-05017; Funding details: Stiftelsen för Strategisk Forskning, SSF, EM16-0013; Funding details: Vetenskapsrådet, VR, 2017-04080; Funding details: Knut och Alice Wallenbergs Stiftelse, KAW2012.0078; Funding text 1: We acknowledge the Knut and Alice Wallenberg Foundation (Project No. KAW2012.0078), the Swedish Research Council (Project No. 2018-05017) and the Swedish Foundation for Strategic Research (Project No. EM16-0013) for their financial support. MR also acknowledges support from the Swedish Research council, VR (Project No. 2017-04080). We gratefully acknowledge the Science and Technology Facilities Council (STFC) for access to neutron beamtime at ISIS (Experiment RB1810114; 10.5286/ISIS.E.RB1810114), the provision of sample preparation and INTER facilities. GP would also like to thank Matthew Fielden for his help with the atomic force microscopy (AFM) measurements at the Nanofabrication facility at the Albanova University Center, Stockholm, Sweden. Dr Manishkumar Shimpi (Luleå University of Technology) is gratefully acknowledged for the synthesis of the IL.
2021-01-192021-01-192023-05-25Bibliographically approved