Preparation of nickel, nickel-iron, and silver-copper nanoparticles in ionic liquids (original) (raw)
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Formation of Nanoparticles Assisted by Ionic Liquids
Handbook of Green Chemistry - Volume 8 – Green Processes – Green Nanoscience, 2012
Imidazolium ionic liquids (ILs) have proven to be a suitable medium for the generation of a myriad of soluble metal nanoparticles (NPs). In particular, transition-metal NPs with small size and a narrow size distribution have been mainly prepared by reduction of organometallic compounds with molecular hydrogen or by decomposition of complexes in the zerovalent state in ILs. The formation and stabilization of nanoparticles in these fluids occurs with reorganization of the hydrogen bond network and the generation of nanostructures with polar and non-polar regions where the NPs are included. The IL forms a protective layer that is probably composed of imidazolium aggregate anions located immediately adjacent to the NP surface-providing the Columbic repulsion and countercations that provide the charge balance. These stable transition metal NPs immobilized in the ILs are considered efficient green catalysts for general reactions in multiphase systems. In this chapter, the synthesis, stabilization, and catalytic applications of metal NPs in ILs and the recyclability of these systems are discussed. 1.1 Metal Nanoparticles in Ionic Liquids: Synthesis Generally, stable and well-dispersed metal NPs have been prepared in ILs by the simple reduction of the M(I-IV) complexes or thermal decomposition of the organometallic precursors in the formal zero oxidation state. Recently, other methods such as the phase transfer of preformed NPs in water or organic solvents to the IL and the bombardment of bulk metal precursors with deposition on the ILs have been reported. However, one of the greatest challenges in the NPs field is to synthesize reproducibly metal NPs with control of the size and shape. Selected studies of the preparation of metal NPs in ILs that, in some cases, provide NPs with different sizes and shapes are considered in this section.
Gold Nanoparticles in Ionic Liquids Prepared by Sputter Deposition
2012
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Physical Chemistry …, 2011
Sputtering deposition of gold onto the 1-(butyronitrile)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BCN)MI·N(Tf)(2) ionic liquid (IL) has generated colloidal and stable gold nanospheres (AuNS) and gold nanodisks (AuND) in a bimodal size distribution. Upon increasing the sputtering discharge voltage, three distinct phenomena were observed: (i) the mean diameter of both AuNS and AuND decreased; (ii) the population with lower diameters increased and (iii) the formation of AuND disappeared at voltages higher than 340 V. By dissolving the colloidal gold nanoparticles (AuNPs) in isopropanol and dropping the product onto carbon-coated Cu grids, 2D and 3D superlattices tended to be formed, as observed by transmission electron microscopy (TEM). Therefore, the formation of AuND is probably related to a strong interaction between sputtered Au atoms of low kinetic energy and the nitrile groups orientated to the vacuum phase of the IL surface, which drives the preferential anisotropi...
ACS Omega, 2017
Gold nanoparticles (Au NPs) have been electrochemically prepared in situ and in vacuo using two different electrochemical device configurations, containing an ionic liquid (IL), N-N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, that serves both as reaction and as stabilizing media for the NPs. It was observed in both devices that Au NPs were created using an anodically triggered route. The created Au NPs are relatively small (3−7 nm) and reside within the IL medium. X-ray photoelectron spectroscopy is utilized to follow not only the formation of the NPs but also their charging/discharging properties, by monitoring the charging shifts of the Au4f peak representing the electrodes and also the Au NPs as well as the F1s peak of the IL after polarizing one of the electrodes. Accordingly, DC polarization across the electrodes leads to a uniform binding energy shift of F1s of the IL along with that of Au4f of the NPs within. Moreover, this shift corresponds to only half of the applied potential. AC polarization brings out another dimension for demonstrating further the harmony between the charging/discharging property of the IL medium and the Au NPs in temporally and laterally resolved fashions. Polarization of the electrodes result in perfect spectral separation of the Au4f peaks of the NPs from those of the metal in both static (DC) and in time-and position-dependent (AC) modes.
Sensors, 2015
A systematic study was carried out to investigate the effect of ionic liquid in solid polymer electrolyte (SPE) and its layer morphology on the characteristics of an electrochemical amperometric nitrogen dioxide sensor. Five different ionic liquids were immobilized into a solid polymer electrolyte and key sensor parameters (sensitivity, response/recovery times, hysteresis and limit of detection) were characterized. The study revealed that the sensor based on 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][N(Tf)2]) showed the best sensitivity, fast response/recovery times, and low sensor response hysteresis. The working electrode, deposited from water-based carbon nanotube ink, was prepared by aerosol-jet printing technology. It was observed that the thermal treatment and crystallinity of poly(vinylidene fluoride) (PVDF) in the solid polymer electrolyte influenced the sensitivity. Picture analysis of the morphology of the SPE layer based on [EMIM][N(Tf)2] ionic liquid treated under different conditions suggests that the sensor sensitivity strongly depends on the fractal dimension of PVDF spherical objects in SPE. Their deformation, e.g., due to crowding, leads to a decrease in sensor sensitivity.
Growth of sputter-deposited gold nanoparticles in ionic liquids
Physical Chemistry Chemical Physics, 2011
The growth of gold nanoparticles (NPs) synthesized by sputter deposition on an ionic liquid surface is studied in situ in the bulk phase of the ionic liquids (ILs) 1-butyl-3-methylimidazolium dicyanamide [C 1 C 4 Im][N(CN) 2 ], 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide [C 1 C 4 Im][Tf 2 N], 1-butyl-3-methylimidazolium tetrafluoroborate [C 1 C 4 Im][BF 4 ], 1-butyl-3methylimidazolium hexafluorophosphate [C 1 C 4 Im][PF 6 ] and 1-butyl-3-methylimidazolium triflate [C 1 C 4 Im][TfO]. It is found that primary nanoparticles with a diameter smaller than 2.5 nm are present in the sample immediately after sputtering. Growth of these primary particles proceeds after the end of the sputtering process and stops when the nanoparticles reach a certain size. Depending on the viscosity of the ionic liquid this growth process can proceed several hours to several days. The growth speed is fastest for the least viscous ionic liquid and follows the trend [also found that a higher concentration of sputtered gold results in faster growth of the gold nanoparticles. A discussion on the growth mechanism of sputtered gold NPs is included.
BioNanoScience, 2013
Nanotechnology is playing an important role in the development of biosensors. The exclusive physical and chemical properties of nanomaterials make them exceptionally suitable for designing new and improved sensing devices, especially electrochemical sensors and biosensors. Room temperature ionic liquids (RTILs) are salts that exist in the liquid phase at and around 298 K and are entirely composed of ions: a bulky, asymmetric organic cation and usually an inorganic anion but some ILs also has organic anion. ILs have received much attention as a replacement for traditional volatile organic solvents as they possess many attractive properties such as intrinsic ion conductivity, low volatility, high chemical and thermal stability, low combustibility, and wide electrochemical windows, etc. Due to negligible or nonzero volatility of these solvents, they are considered "greener" for the environment in comparison to volatile organic compounds. ILs have been widely used in electrodeposition, electrosynthesis, electrocatalysis, electrochemical capacitor, lubricants, plasticizers, solvent, lithium batteries, solvents to manufacture nanomaterials, extraction, gas absorption agents etc. [1-4]. This review discusses the electrochemical sensors and biosensors based on carbon nanotubes, metal oxide nanoparticles, and ionic liquid/composite modified electrodes. The main thrust of the review is to present an overview on the advantages of use of RTILs along with nanomaterials for electrochemical sensors and biosensors. Consequently, recent developments and major strategies for enhancing sensing performance have been thoroughly discussed.