Investigation of thermodynamics, and structural, dynamical, and electrical properties of polyoxometalate ionic liquid confined into carbon nanotubes during the melting process using molecular dynamics simulation.

Understanding the properties of ionic liquids confined into nano-pores is required to use ionic liquids for many applications such as electrolytes for energy storage in capacitors and solar cells. Recently, polyoxometalate ionic liquids have attracted much attention for their potential applications in electrochemistry, catalysis, and nanotechnology. In this work, we have performed MD simulations on 1-ethyl-3-methylimidazolium Keggin ([emim]3[PW12O40]) confined into armchair (20,20) CNTs to study the thermal properties and melting process. Changes in the simulated results of configurational energy of confined polyoxometallate IL indicated that the melting range of the confined polyoxometalate IL is about 650-750 K. Heat capacity at constant volume of the confined IL is about 2 (cal K-1 mol-1) which shows sharp changes around the melting range. The average number of hydrogen bonds (〈HB〉) of the confined IL is about 2.8 which also presents sharp changes around the melting range. The ion conductivity and self-diffusion coefficient of [emim]3[PW12O40] IL also present a sharp maximum of 25 (S m-1) and 6 × 10-10 (m2 s-1) at the melting point. Our results did not show a significant hysteresis in the melting process and therefore, the process is reversible. Our simulation also indicated that the confinement of the polyoxometallate IL into the CNT increases its thermal stability and melting point. Our simulations also indicated that the type of CNT configuration has a small effect on the melting point of the confined polyoxometallate IL.

A novel nanocomposite (g-C3N4/Fe3O4@P2W15V3) with dual function in organic dyes degradation and cysteine sensing.

Among the important needs of human societies is the elimination of environmental pollution and also the construction of high-performance and inexpensive biosensors. In this regard, the construction of multi-functional composites has been considered. A novel magnetic graphite carbon nitride decorated by tri-vanadium substituted Dawson-type heteropolytungstate nanocomposite (C3N4/Fe3O4@P2W15V3) effectively synthesized and characterized by prevalent functional analysis. The prepared nano-catalyst presents bi-functional usage involving photocatalytic removal of dyes (methylene blue, congo red and phenyl red) (around 98%) under visible light radiation and greatly sensitive colorimetric sensing of cysteine in an aqueous media. Moreover, synthesized nano-catalyst successfully recovered five times without any considerable deficiency on its photocatalytic ability. Further, Moreover, we propose a novel method for cysteine detection based on the C3N4/Fe3O4@P2W15V3 nanocomposite. This nanocomposite displayed a privileged catalytic feature for cysteine oxidation to extend a clock reaction of methylene blue as an indicator in the presence of NaBH4 in acidic solution. More importantly, this colorimetric sensing method of cysteine presents an easy, low-cost, selective, and rapid colorimetric assay with a detection limit value of 7.2 µM in the acceptable linear range of 5-600 µM.