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Nanoscale capillary freezing of ionic liquids confined between metallic interfaces and the role of electronic screening

Abstract

Room-temperature ionic liquids (RTILs) are new materials with fundamental importance for energy storage and active lubrication. They are unusual liquids, which challenge the classical frameworks of electrolytes, whose behaviour at electrified interfaces remains elusive, with exotic responses relevant to their electrochemical activity. Using tuning-fork-based atomic force microscope nanorheological measurements, we explore here the properties of confined RTILs, unveiling a dramatic change of the RTIL towards a solid-like phase below a threshold thickness, pointing to capillary freezing in confinement. This threshold is related to the metallic nature of the confining materials, with more metallic surfaces facilitating freezing. This behaviour is interpreted in terms of the shift of the freezing transition, taking into account the influence of the electronic screening on RTIL wetting of the confining surfaces. Our findings provide fresh views on the properties of confined RTIL with implications for their properties inside nanoporous metallic structures, and suggests applications to tune nanoscale lubrication with phase-changing RTILs, by varying the nature and patterning of the substrate, and application of active polarization.

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Figure 1: Experimental set-up.
Figure 2: Confinement-induced freezing transition.
Figure 3: Effect of substrate electronic properties on the freezing transition.
Figure 4: Voltage-induced freezing.

References

  1. Armand, M., Endres, F., MacFarlane, D. R., Ohno, H. & Scrosati, B. Ionic-liquid materials for the electrochemical challenges of the future. Nat. Mater. 8, 621–629 (2009).

    CAS  Article  Google Scholar 

  2. Uesugi, E., Goto, H., Eguchi, R., Fujiwara, A. & Kubozono, Y. Electric double-layer capacitance between an ionic liquid and few-layer graphene. Sci. Rep. 3, 1595 (2013).

    Article  Google Scholar 

  3. Palacio, M. & Bhushan, B. A review of ionic liquids for green molecular lubrication in nanotechnology. Tribol. Lett. 40, 247–268 (2010).

    CAS  Article  Google Scholar 

  4. Dold, C., Amann, T. & Kailer, A. Influence of electric potentials on friction of sliding contacts lubricated by an ionic liquid. Phys. Chem. Chem. Phys. 17, 10339–10342 (2015).

    CAS  Article  Google Scholar 

  5. Smith, A. M., Lovelock, K. R. J., Gosvami, N. N., Welton, T. & Perkin, S. Quantized friction across ionic liquid thin films. Phys. Chem. Chem. Phys. 15, 15317–15320 (2013).

    CAS  Article  Google Scholar 

  6. Siria, A. et al. Giant osmotic energy conversion measured in a single transmembrane boron nitride nanotube. Nature 494, 455–458 (2013).

    CAS  Article  Google Scholar 

  7. Bocquet, L. & Charlaix, E. Nanofluidics, from bulk to interfaces. Chem. Soc. Rev. 39, 1073–1095 (2010).

    CAS  Google Scholar 

  8. Secchi, E., Niguès, A., Jubin, L., Siria, A. & Bocquet, L. Scaling behavior for ionic transport and its fluctuations in individual carbon nanotubes. Phys. Rev. Lett. 116, 154501 (2016).

    Article  Google Scholar 

  9. Secchi, E. et al. Massive radius-dependent flow slippage in single carbon nanotubes. Nature 537, 210–213 (2016).

    CAS  Article  Google Scholar 

  10. Agrawal, K. V., Shimizu, S., Drahushuk, L. W., Kilcoyne, D. & Strano, M. S. Observation of extreme phase transition temperatures of water confined inside isolated carbon nanotubes. Nat. Nanotech. 12, 267–273 (2017).

    CAS  Article  Google Scholar 

  11. Fedorov, M. V. & Kornyshev, A. A. Ionic liquids at electrified interfaces. Chem. Rev. 114, 2978–3036 (2014).

    CAS  Article  Google Scholar 

  12. Merlet, C. et al. On the molecular origin of supercapacitance in nanoporous carbon electrodes. Nat. Mater. 11, 306–310 (2012).

    CAS  Article  Google Scholar 

  13. Perkin, S., Salanne, M., Madden, P. & Lynden-Bell, R. Is a Stern and diffuse layer model appropriate to ionic liquids at surfaces? Proc. Natl Acad. Sci. USA 110, E4121 (2013).

    CAS  Article  Google Scholar 

  14. Atkin, R. et al. AFM and STM studies on the surface interaction of [BMP]TFSA and (EMIm]TFSA ionic liquids with Au(111). J. Phys. Chem. C 113, 13266–13272 (2009).

    CAS  Article  Google Scholar 

  15. Rotenberg, B. & Salanne, M. Structural transitions at ionic liquids interfaces. J. Phys. Chem. Lett. 6, 4978–4985 (2015).

    CAS  Article  Google Scholar 

  16. Endres, F., Borisenko, N., El Abedin, S. Z., Hayes, R. & Atkin, R. The interface ionic liquid(s)/electrode(s): in situ STM and AFM measurements. Faraday Discuss. 154, 221–233 (2012).

    CAS  Article  Google Scholar 

  17. Borisenko, N., Atkin, R., Lahiri, A., El Abedin, S. Z. & Endres, F. Effect of dissolved LiCl on the ionic liquid-Au(111) interface: an in situ STM study. J. Phys. Condens. 26, 284111 (2014).

    Article  Google Scholar 

  18. Liu, Y., Zhang, Y., Wu, G. & Hu, J. Coexistence of liquid and solid phases of Bmim-PF6 ionic liquid on mica surfaces at room temperature. J. Am. Chem. Soc. 128, 7456–7457 (2006).

    CAS  Article  Google Scholar 

  19. Bovio, S., Podestà, A., Milani, P., Ballone, P. & Del Pópolo, M. G. Nanometric ionic-liquid films on silica: a joint experimental and computational study. J. Phys. Condens. Matter 21, 424118 (2009).

    CAS  Article  Google Scholar 

  20. Bovio, S., Podesta, A., Lenardi, C. & Milani, P. Evidence of extended solidlike layering in [Bmim][NTf2] ionic liquid thin films at room-temperature. J. Phys. Chem. B 113, 6600–6603 (2009).

    CAS  Article  Google Scholar 

  21. Yokota, Y., Harada, T. & Fukui, K. I. Direct observation of layered structures at ionic liquid/solid interfaces by using frequency-modulation atomic force microscopy. Chem. Commun. 46, 8627–8629 (2010).

    CAS  Article  Google Scholar 

  22. Lee, A. A. & Perkin, S. Ion-image interactions and phase-transition at electrolyte-metal interface. J. Phys. Chem. Lett. 7, 2753–2757 (2016).

    CAS  Article  Google Scholar 

  23. Ueno, K., Kasuya, M., Watanabe, M., Mizukami, M. & Kurihara, K. Resonance shear measurement of nanoconfined ionic liquids. Phys. Chem. Chem. Phys. 12, 4066–4071 (2010).

    CAS  Article  Google Scholar 

  24. Jurado, L. A. et al. Irreversible structural change of a dry ionic liquid under nanoconfinement. Phys. Chem. Chem. Phys. 17, 13613–13624 (2015).

    CAS  Article  Google Scholar 

  25. Bou-Malham, I. & Bureau, L. Nanoconfined ionic liquids: effect of surface charges on flow and molecular layering. Soft Matter 6, 4062–4065 (2010).

    CAS  Article  Google Scholar 

  26. Niguès, A., Siria, A., Vincent, P., Poncharal, P. & Bocquet, L. Ultra-high interlayer friction inside boron-nitride nanotubes. Nat. Mater. 13, 688–693 (2014).

    Article  Google Scholar 

  27. O’Mahony, A. M., Silvester, D. S., Aldous, L., Hardacre, C. & Compton, R. G. Effect of water on the electrochemical window and potential limits of room-temperature ionic liquids. J. Chem. Eng. Data 53, 2884–2891 (2008).

    Article  Google Scholar 

  28. Morita, M., Ohmi, T., Hasegawa, E., Kawakami, M. & Ohwada, M. Growth of native oxide on a silicon surface. J. Appl. Phys. 68, 1272–1281 (1990).

    CAS  Article  Google Scholar 

  29. Anson, F. C. & Lingane, J. J. Chemical evidence for oxide films on platinum electrometric electrodes. J. Am. Chem. Soc. 79, 4901–4904 (1957).

    CAS  Article  Google Scholar 

  30. Smith, A. M., Lee, A. A. & Perkin, S. The electrostatic screening length in concentrated electrolytes increases with concentration. J. Phys. Chem. Lett. 7, 2157–2163 (2016).

    CAS  Article  Google Scholar 

  31. Gebbie, M. A. et al. Long range electrostatic forces in ionic liquids. Chem. Commun. (2017).

  32. Leroy, S. & Charlaix, E. Hydrodynamic interactions for the measurement of thin film elastic properties. J. Fluid Mech. 674, 389–407 (2011).

    CAS  Article  Google Scholar 

  33. Elbourne, A. et al. Nanostructure of the ionic liquid—graphite stern layer. ACS Nano 9, 7608–7620 (2015).

    CAS  Google Scholar 

  34. Buchner, F., Forster-Tonigold, K., Bozorgchenani, M., Gross, A. & Jürgen Behm, R. Interaction of a self assembled ionic liquid layer with graphite (0001): a combined experimental and theoretical study. J. Phys. Chem. Lett. 7, 226–233 (2016).

    CAS  Article  Google Scholar 

  35. Alba-Simionesco, C. et al. Effects of confinement on freezing and melting. J. Phys. Condens. Matter 18, R15 (2006).

    CAS  Article  Google Scholar 

  36. Bhatt, V. D., Gohi, K. & Mishra, A. Thermal energy storage capacity of some phase changing materials and ionic liquids. Int. J. ChemTech Res. 2, 1771e9 (2010).

    Google Scholar 

  37. Mahan, G. D. Many-Particle Physics (Springer Science and Business Media, 2000).

    Book  Google Scholar 

  38. Dibrov, S. M. & Koch, J. K. Crystallographic view of fluidicstructures for room-temperatureionic liquids: 1-butyl-3-methyl-imidazolium hexafluorophosphat. ActaCryst. C 62, o19-o21 (2006).

    Google Scholar 

  39. Alam, M. T., Islam, M. M., Okajima, T. & Ohsaka, T. Capacitance measurements in a series of room-temperature ionic liquids at glassy carbon and gold electrode interfaces. J. Phys. Chem. C 112, 16600–16608 (2008).

    CAS  Article  Google Scholar 

  40. Sweeney, J. et al. Control of nanoscale friction on gold in an ionic liquid by a potential-dependent ionic lubricant layer. Phys. Rev. Lett. 109, 155502 (2012).

    Article  Google Scholar 

  41. Li, H., Wood, R. J., Rutland, M. W. & Atkin, R. An ionic liquid lubricant enables superlubricity to be switched in situ using an electrical potential. Chem. Commun. 50, 4368–4370 (2014).

    CAS  Article  Google Scholar 

  42. Fajardo, O. Y., Bresme, F., Kornyshev, A. A. & Urbakh, M. Electrotunable lubricity with ionic liquid nanoscale films. Sci. Rep. 5, 7698 (2015).

    CAS  Article  Google Scholar 

  43. Fajardo, O. Y., Bresme, F., Kornyshev, A. A. & Urbakh, M. Electrotunable friction with ionic liquid lubricants: how important is the molecular structure of the ions? J. Phys. Chem. Lett. 6, 3998–4004 (2015).

    CAS  Article  Google Scholar 

  44. Kondrat, S., Wu, P., Qiao, R. & Kornyshev, A. A. Accelerating charging dynamics in subnanometre pores. Nat. Mater. 13, 387–393 (2014).

    CAS  Article  Google Scholar 

  45. Kondrat, S., Georgi, N., Fedorov, M. V. & Kornyshev, A. A. A superionic state in nano-porous double-layer capacitors: insights from Monte Carlo simulations. Phys. Chem. Chem. Phys. 13, 11359–11366 (2011).

    CAS  Article  Google Scholar 

  46. Kondrat, S. & Kornyshev, A. Superionic state in double-layer capacitors with nanoporous electrodes. J. Phys. Condens. Matter 23, 022201 (2010).

    Article  Google Scholar 

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Acknowledgements

L.B. and A.S. thank B. Rotenberg, B. Cross and E. Charlaix for many fruitful discussions. J.C., A.N. and A.S. acknowledge funding from the European Union’s H2020 Framework Programme/ERC Starting Grant agreement number 637748 - NanoSOFT. L.B. acknowledges support from the European Union’s FP7 Framework Programme/ERC Advanced Grant Micromegas. L.B. acknowledges funding from a PSL chair of excellence. The authors acknowledge funding from ANR project BlueEnergy.

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A.S. and L.B. conceived and directed the research. J.C. performed the experiments and analysed the data. A.N., L.B. and A.S., supervised the experiments. V.K., B.C., A.S. and L.B. conducted the theoretical analysis and B.C. performed the molecular simulations. All authors contributed to the scientific discussions and the preparation of the manuscript.

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Correspondence to Alessandro Siria.

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The authors declare no competing financial interests.

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Comtet, J., Niguès, A., Kaiser, V. et al. Nanoscale capillary freezing of ionic liquids confined between metallic interfaces and the role of electronic screening. Nature Mater 16, 634–639 (2017). https://doi.org/10.1038/nmat4880

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