Dr Hua Li
School of Environmental and Life Sciences
Upon completing my PhD studies in Applied Science (Minerals and Materials), at Ian Wark Research Institute, University of South Australia in 2012, I was employed as a Postdoctoral Research Associate in the Discipline of Chemistry, University of Newcastle. In January 2015 I was appointed to a full-time lecturing position in the same discipline. Currently, my research focuses on developing new and high-performance ionic liquid based lubricants, including:
- Nanostructure and Nanotribology (Nanofriction) of Ionic Liquids
As ionic liquids are composed solely of cations and anions, lubricity can be externally controlled in situ by application of a potential to an electrode surface. The ion composition in the boundary layer responds with the applied potential, and thus alters lubricity.
Experimental results will be correlated to computational simulations, so as to reveal the details of the boundary layer and how nanotribology alters with the boundary layer structure at the ionic liquid-electrode interface.
- Ionic Liquids as Lubricant Additives
Pure ionic liquids are very expensive. The high cost limits their extensive application in industry. The problem can be solved by applying ionic liquids as lubricant additives, where small amounts can markedly improve the tribological performance of commercially cheap base oils.
Tribology (friction) at both nanoscale and macroscale will be investigated so as to reveal how the ions of ionic liquids alter the lubricity at the oil-solid interfaces. The details of my research focus are described in the attached research proposal.
Linking tribological performance at the nanoscale and macroscale remains a considerable challenge for the development of new and more effective lubricants. The tuneable nature of ionic liquids enables cause – effect relationships to be teased out in ways not possible for conventional lubricants, meaning that I am well places to address this issue.
- Master of Engineering (Biomedical Engineering), Tianjin University - China
- Bachelor of Science / Bachelor of Arts, Tianjin University - China
- Diploma in Material Chemistry, Tianjin University - China
- Diploma in Biomedical Engineering, Tianjin University - China
Fields of Research
|020499||Condensed Matter Physics not elsewhere classified||20|
|030699||Physical Chemistry not elsewhere classified||40|
|030399||Macromolecular and Materials Chemistry not elsewhere classified||40|
|Title||Organisation / Department|
|Lecturer||University of Newcastle
School of Environmental and Life Sciences
For publications that are currently unpublished or in-press, details are shown in italics.
Journal article (14 outputs)
McLean B, Li H, Stefanovic R, Wood RJ, Webber GB, Ueno K, et al., 'Nanostructure of [Li(G4)] TFSI and [Li(G4)] NO3 solvate ionic liquids at HOPG and Au(111) electrode interfaces as a function of potential', PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 17 325-333 (2015)
Li H, Atkin R, Page AJ, 'Combined Friction Force Microscopy and Quantum Chemical Investigation of the Tribotronic Response at the Propylammonium NitrateÂ¿Graphite Interface', Physical Chemistry Chemical Physics, 17 16047-16052 (2015) [C1]
Li H, Cooper PK, Somers AE, Rutland MW, Howlett PC, Forsyth M, Atkin R, 'Ionic liquid adsorption and nanotribology at the silica-oil interface: Hundred-fold dilution in oil lubricates as effectively as the pure ionic liquid', Journal of Physical Chemistry Letters, 5 4095-4099 (2014) [C1]
The remarkable physical properties of ionic liquids (ILs) make them potentially excellent lubricants. One of the challenges for using ILs as lubricants is their high cost. In this... [more]
The remarkable physical properties of ionic liquids (ILs) make them potentially excellent lubricants. One of the challenges for using ILs as lubricants is their high cost. In this article, atomic force microscopy (AFM) nanotribology measurements reveal that a 1 mol % solution of IL dissolved in an oil lubricates the silica surface as effectively as the pure IL. The adsorption isotherm shows that the IL surface excess need only be approximately half of the saturation value to prevent surface contact and effectively lubricate the sliding surfaces. Using ILs in this way makes them viable for large-scale applications.
Li H, Wood RJ, Endres F, Atkin R, 'Influence of alkyl chain length and anion species on ionic liquid structure at the graphite interface as a function of applied potential', Journal of Physics Condensed Matter, 26 (2014) [C1]
Atomic force microscopy (AFM) force measurements elucidate the effect of cation alkyl chain length and the anion species on ionic liquid (IL) interfacial structure at highly order... [more]
Atomic force microscopy (AFM) force measurements elucidate the effect of cation alkyl chain length and the anion species on ionic liquid (IL) interfacial structure at highly ordered pyrolytic graphite (HOPG) surfaces as a function of potential. Three ILs are examined: 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM] FAP), 1-ethyl-3- methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([EMIM] FAP), and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM] TFSA). The step-wise force-distance profiles indicate the ILs adopt a multilayered morphology near the surface. When the surface is biased positively or negatively versus Pt quasireference electrode, both the number of steps, and the force required to rupture each step increase, indicating stronger interfacial structure. At all potentials, push-through forces for [HMIM] FAP are the highest, because the long alkyl chain results in strong cohesive interactions between cations, leading to well-formed layers that resist the AFM tip. The most layers are observed for [EMIM] FAP, because the C2 chains are relatively rigid and the dimensions of the cation and anion are similar, facilitating neat packing. [EMIM] TFSA has the smallest push-through forces and fewest layers, and thus the weakest interfacial structure. Surface-tip attractive forces are measured for all ILs. At the same potential, the attractions are the strongest for [EMIM] TFSA and the weakest for [HMIM] FAP because the interfacial layers are better formed for the longer alkyl chain cation. This means interfacial forces are stronger, which masks the weak attractive forces. Â© 2014 IOP Publishing Ltd.
Carstens T, Gustus R, HÃ¶fft O, Borisenko N, Endres F, Li H, et al., 'Combined STM, AFM, and DFT study of the highly ordered pyrolytic graphite/1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide interface', Journal of Physical Chemistry C, 118 10833-10843 (2014) [C1]
The highly ordered pyrolytic graphite (HOPG)/1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([OMIm]Tf2N) interface is examined by ultrahigh vacuum scanning tunnelin... [more]
The highly ordered pyrolytic graphite (HOPG)/1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([OMIm]Tf2N) interface is examined by ultrahigh vacuum scanning tunneling microscopy (UHV-STM), atomic force microscopy (UHV-AFM) (and as a function of potential by in situ scanning tunneling microscopy (STM)), in situ atomic force microscopy (AFM), and density functional theory (DFT) calculations. In situ STM and AFM results reveal that multiple ionic liquid (IL) layers are present at the HOPG/electrode interface at all potentials. At open-circuit potential (OCP), attractions between the cation alkyl chain and the HOPG surface result in the ion layer bound to the surface being cation rich. As the potential is varied, the relative concentrations of cations and anions in the surface layer change: as the potential is made more positive, anions are preferentially adsorbed at the surface, while at negative potentials the surface layer is cation rich. At -2 V an unusual overstructure forms. STM images and AFM friction force microscopy measurements both confirm that the roughness of this overstructure increases with time. DFT calculations reveal that [OMIm]+ is attracted to the graphite surface at OCP; however, adsorption is enhanced at negative potentials due to favorable electrostatic interactions, and at -2 V the surface layer is cation rich and strongly bound. The energetically most favorable orientation within this layer is with the [OMIm]+ octyl chains aligned "epitaxially" along the graphitic lattice. This induces quasi-crystallization of cations on the graphite surface and formation of the overstructure. An alternative explanation may be that, because of the bulkiness of the cation sitting along the surface, a single layer of cations is unable to quench the surface potential, so a second layer forms. The most energetically favorable way to do this might be in a quasi-crystalline/multilayered fashion. It could also be a combination of strong surface binding/orientations and the need for multilayers to quench the charge. Â© 2014 American Chemical Society.
Li H, Wood RJ, Rutland MW, Atkin R, 'An ionic liquid lubricant enables superlubricity to be "switched on" in situ using an electrical potential.', Chem Commun (Camb), 50 4368-4370 (2014) [C1]
Li H, Rutland MW, Atkin R, 'Ionic liquid lubrication: Influence of ion structure, surface potential and sliding velocity', Physical Chemistry Chemical Physics, 15 14616-14623 (2013) [C1]
Li H, Endres F, Atkin R, 'Effect of alkyl chain length and anion species on the interfacial nanostructure of ionic liquids at the Au(111)-ionic liquid interface as a function of potential', Physical Chemistry Chemical Physics, 15 14624-14633 (2013) [C1]
|Show 11 more journal articles|
Conference (1 outputs)
Atkin R, Li H, Sweeney J, Elbourne A, Webber G, Rutland M, Warr GG, 'Effect of surface nanostructure and ion structure on the nanotribology of the graphite: Ionic liquid interface', ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, San Francisco, CA (2014) [E3]
Grants and Funding
|Number of grants||1|
Click on a grant title below to expand the full details for that specific grant.
20151 grants / $7,291
Funding body: University of Newcastle - Faculty of Science & IT
|Funding body||University of Newcastle - Faculty of Science & IT|
|Scheme||Strategic Small Grant|
|Type Of Funding||Internal|