Pressure-enhanced surface interactions between nano-TiO₂ and ionic liquid mixtures probed by high pressure IR spectroscopy

Abstract

The pressure-dependent interactions between the ionic liquid mixture ([MPI][I1.5]) and nano-TiO2 surfaces have been studied up to 2.5 GPa. The results of infrared spectroscopic profiles of [MPI][I1.5] and [MPI][I1.5]-nano-TiO2 indicated that no appreciable changes in the C-H stretching bands with the addition of nano-TiO2 were observed under ambient pressure. As the pressure was elevated to 0.7 GPa, the C-H stretching absorption of [MPI][I1.5] underwent band-narrowing and red-shifts in frequency. In contrast to the results of [MPI][I1.5], the spectra of [MPI][I1.5]-nano-TiO2 do not show dramatic changes under high pressures. A possible explanation for this observation is the formation of certain pressure-enhanced C-H···nano-TiO2 interactions around the imidazolium C-H and alkyl C-H groups. As imidazolium C-H···I(-) is replaced by the weaker imidazolium C-H···polyiodide, the splitting of the imidazolium C-H stretching bands was observed. The experimental results indicate that both nano-TiO2 and polyiodides are capable of disturbing the self-assembly of ionic liquids. This study suggests the possibility to tune the efficiency of dye-sensitized solar cells via a high pressure method.

A high pressure pathway toward boron-based nanostructured solids

“…Current HP studies on nanoparticles deal with two families of solids: (1) metal oxides by applying HP only and no heating, [11][12][13][14] (2) light element B, C, or N-based non-oxides that crystallize only under both HP and HT. 7,[15][16][17] In the latter case, nanostructuration increases hardness toward ultrahard materials (e.g.…”

“…Remarkably, up to now only scarce reports have described the synthesis of nanostructured inorganic materials under HP-HT conditions. [11][12][13][14]51 Indeed, such treatments usually yield reduced interfaces by large crystal growth. Our striking result arises from two kinetic factors.…”

Hybrid Structure of Ionic Liquid and TiO2 Nanoclusters for Efficient Hydrogen Evolution Reaction

“…Metal oxide semiconductors have also been used as photocatalytic materials for water splitting as TiO 2 was the first semiconducting material that was used for the same . Both ILs and TiO 2 nanostructures represent two distinct classes of materials that have been extensively explored by many researchers as potential materials for the application in the field of energy storage and conversion. ,, Hybrid structures of various room-temperature ILs (RTILs) and TiO 2 nanostructures have been recently studied at the fundamental level using various spectroscopic techniques. − Recently, Binetti et al have analyzed the interaction of TiO 2 nanorods with imidazolium-based ILs with variable alkyl chain lengths (C n mim BF 4 with n = 2, 4, 6, and 10 and C n mim PF 6 with n = 4, 6, and 10) by UV–vis absorption and photoluminescence (PL) emission spectroscopy along with time-resolved PL . Based on the observation of charge-transfer processes between the RTILs and TiO 2 nanorods, the authors have predicted that these hybrid materials would be suitable for designing modern batteries and solar cells .…”

Utilizing Infrared Spectroscopy to Analyze the Interfacial Structures of Ionic Liquids/Al2O3 and Ionic Liquids/Mica Mixtures under High Pressures

“…Therefore, IR methodologies may be useful to probe the structures of ionic liquids at solid surfaces. Furthermore, it can be seen from some studies that there are weak hydrogen bonds between the aromatic C–H in the cations and the anions [36,37,38,39,40]. Moreover, the contribution to charge-assisted hydrogen bond energy by coulombic interactions is especially significant and the C–H…O hydrogen bonding in 1,3-dimethylimidazolium methyl sulfate is one of the dominating interactions [32].…”