The isobaric and isochoric heat capacities of six disubstituted imidazolium-based ionic liquids with different anions and two trisubstituted imidazolium-based bis-(trifluoromethylsulfonyl)imides were determined at atmospheric pressure in the temperature range from 293.15 to 323.15 K. The isobaric heat capacities were determined using differential scanning calorimetry. The isochoric heat capacities were determined indirectly by means of the acoustic method from the speed of sound and density measurements. Also, other connected with the speed of sound quantities such as isentropic and isothermal compressibilities as well as internal pressures were determined. The highest compressibilities show both trisubstituted imidazolium-based bis(trifluoromethylsulfonyl)imides whereas 1-ethyl-3-methylimidazolium thiocyanate shows the lowest compressibility. The critical comparison of the isobaric heat capacity data with the available literature data makes possible a recommendation of the most reliable heat capacity values. Analyzed predictive capability of two heat capacity models based on the group contribution method is poor in the case of the [C(CN) 3 ] − anion. Additionally, based on the speeds of sound, the thermal conductivities were calculated using a modified Bridgman relation and compared with values estimated by a group contribution method. Here, the worst results are obtained in the case of [SCN] − anion.
The goal of the presented investigation was to study the differences in the decoration of graphene sheets, having various amounts of oxygen containing functional groups, with silver nanoparticles (AgNPs). The reduction of graphehe oxide (GO) was performed with the use of ascorbic acid (AA), leading to partiallyreduced graphene oxide (PRGO) and reduced graphene oxide (RGO). The reduction process was monitored and confirmed by Raman Spectroscopy and Fourier Transform -Infrared Spectroscopy (FT-IR). The level of oxygen functional groups in the respective types of graphene was controlled by the duration of the reduction reactions. One-step synthesis of silver nanoparticles (AgNPs) was performed with no additional reducing agents in dark conditions in situ, i.e. directly on the graphene sheets deposited on a silicon wafer. It was proved that the presence of oxygen moieties on the graphene surface provides reactive sites for the spontaneous chemical reduction of Ag + ions. It was also demonstrated that the amount of oxygen moieties on the surface of graphene plays an important role in the nucleation and growth of AgNPs. Moreover, it was found that the number of AgNPs investigated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) increases with the amount of oxygen moieties, while their size decreases. Finally, it was found that the intensity of Raman bands characteristic of graphene are strongly increased for samples with AgNPs, due to surface enhancement Raman scattering (SERS).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.