Liquid-liquid Interfacial Precipitation Research Articles

Catalytic activity of hybrid platinum nanoparticle-[C60]fullerene nanowhisker composites for 4-nitrophenol reduction

Composites comprising platinum nanoparticles loaded on [C60]fullerene nanowhiskers were prepared by a liquid-liquid interfacial precipitation method. The synthesized platinum nanoparticle-[C60]fullerene nanowhisker composites were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The catalytic activity of the platinum nanoparticle-[C60]fullerene nanowhisker composites was confirmed for the reduction of 4-nitrophenol by UV–vis spectroscopy. The reduction of 4-nitrophenol catalyzed by the platinum nanoparticle-[C60]fullerene nanowhisker composites followed the pseudo-first-order reaction rate law.

Catalytic activity of nickel(II) oxide nanoparticle-[C60]fullerene nanowhisker composite for reduction of 4-nitroaniline

Nickel(II) oxide nanoparticles were prepared using the sol-gel method. Subsequently, a nickel(II) oxide nanoparticle-[C60]fullerene nanowhisker composite was synthesized using the nickel oxide(II) nanoparticle dispersion, C60-saturated toluene, and isopropyl alcohol via the liquid-liquid interfacial precipitation (LLIP) method. The resulting composite was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM). The catalytic activity of the nickel(II) oxide nanoparticle-[C60] fullerene nanowhisker composite for 4-nitroaniline reduction was evaluated with ultraviolet-visible (UV-vis) spectroscopy. The kinetic study confirmed that the reduction of 4-nitroaniline using the hybrid nanocomposite followed a pseudo-first order reaction.

One-Dimensional Fullerene/Porphyrin Cocrystals: Near-Infrared Light Sensing through Component Interactions.

Recently, organic donor-acceptor (D-A) cocrystals have attracted special interest as functional materials because of their unique chemical and physical properties that are not exhibited by simple mixtures of their components. Herein, we report the preparation of one-dimensional novel D-A cocrystals from C60 and 5,10,15,20-tetrakis(3,5-dimethoxyphenyl)porphyrin (3,5-TPP); these cocrystals have near-infrared (NIR) light-sensing abilities, despite each of their component molecule individually having no NIR light-sensing properties. Micrometer-sized rectangular columnar C60-3,5-TPP cocrystals were produced by a simple liquid-liquid interfacial precipitation method. The cocrystals exhibit a new strong transition in the NIR region indicative of the existence of charge-transfer interactions between C60 and 3,5-TPP in the cocrystals. The C60-3,5-TPP cocrystals showed n-type transport characteristics with NIR light-sensing properties when the cocrystals were incorporated in bottom-gate/bottom-contact organic phototransistors, revealing that organic cocrystals with suitable charge-transfer interaction are useful as functional materials for the creation of novel NIR-light-sensing devices.

Preparation of [C60]fullerene nanowhisker–cadmium sulfide nanoparticle composite and its photocatalytic activity for degradation of rhodamine B

Cadmium sulfide (CdS) nanoparticles were synthesized from cadmium sulfate (CdSO4), sodium hydroxide (NaOH), and sodium sulfide (Na2S) dissolved into distilled water, and the resulting solution was refluxed for 5 h. The precipitate was collected by centrifugation and dried at 100 °C for 12 h to obtain solid state CdS nanoparticles. The CdS nanoparticle solution was prepared by dissolving powdered CdS nanoparticles in an aqueous solution with the surfactant polyvinyl pyrrolidone (PVP). The [C60]Fullerene nanowhisker–CdS nanoparticle composite was prepared by the liquid–liquid interfacial precipitation (LLIP) method using C60-saturated toluene, the CdS nanoparticle solution, and isopropyl alcohol. The product of the [C60]fullerene nanowhisker–CdS nanoparticle composite was characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and transmission electron microscopy. The photocatalytic activity of the [C60]fullerene nanowhisker–CdS nanoparticle composite assessed through degradation of Rhodamine B (RhB) was confirmed by UV–vis spectroscopy.

Hierarchically-organized C60 crystals obtained from a liquid/liquid interfacial precipitation method by using 1,2,3,4-tetrahydronaphthalene as a solvent

C60 crystals have potential applications in the optoelectronics, photoconducting devices and templated synthesis fields. However, their preparation is complex. A simple liquid-liquid interfacial precipitation method was used to fabricate hierarchically-organized C60 crystals with various topographic characteristics, using 1,2,3,4-tetrahydronaphthalene as a good solvent, and isopropanol, ethanol or methanol as a poor solvent. Results indicate that the morphology and shape of the as-prepared C60 crystals vary according to the solvent combination and the ratio of good to poor solvents. The SEM images of fractured surfaces and XRD patterns of the crystals reveal that the crystals are formed by the hierarchical organization of C60 molecules at the molecular level to nanocrystals that are assembled into micrometer crystals. The crystals are composed solely of C60 molecules, without polymerization and solvents, which are arranged in a face-centered cubic lattice. The surface roughness is increased by post washing with ethanol. The methodology described here is advantageous over the high-temperature conversion and solvent annealing methods reported previously.

Solvent-mediated phase transformation of C60 crystals with well-defined hexagonal shape

CCl4-solvated C60 crystals with hexagonal shape were grown by the liquid-liquid interfacial precipitation method with CCl4 and toluene as poor and good solvents, respectively. Interestingly, the morphology of the hexagonal crystals with the growth liquid are drastically changed with drying in air. A lot of fine rod crystals appear over the original crystals with air-drying, whereas the hexagonal outline of the original crystals is kept even after the transformation. Such change in the morphology is explained by the solvent-mediated phase transformation due to the dissolution of the original crystals by toluene and then re-precipitation of the rod crystals.

Control over Tuning Fullerene Microcrystals by Means of Engineering Charge-Transfer Interactions.

Multifunctional fullerene microcrystals have been prepared by the involvement of water in the liquid-liquid interfacial precipitation. The resulting microcrystals were characterized microscopically and spectroscopically. The role of water in engineering charge-transfer interactions between fullerenes and electron-donating solvents has been corroborated through thermogravimetric and transient absorption spectroscopy analyses.

Preparation of [C60]fullerene nanowhisker-silver nanoparticle composites and their catalytic activities for the oxidation of tetramethylbenzidine with hydrogen peroxide

Trisodium citrate dihydrate (C6H5Na3O7·2H2O), sodium borohydride (NaBH4), cetyltrimethyl ammonium bromide (CTAB, (C16H33)N(CH3)3Br), ascorbic acid (C6H8O6), and silver nitrate (AgNO3) were mixed in distilled water, and the resulting solution was irradiated by ultrasonication for 3 h to obtain silver nanoparticles. Liquid-liquid interfacial precipitation was used to prepare [C60]fullerene nanowhisker-silver nanoparticle composites with C60-saturated toluene, the prepared silver nanoparticles solution, and isopropyl alcohol. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to characterize the [C60]fullerene nanowhisker-silver nanoparticle composites. In the oxidative reaction of tetramethylbenzidine (TMB) with H2O2, the catalytic activity of [C60]fullerene nanowhisker-silver nanoparticle composites was validated by UV-vis spectroscopy.

Controlling Intermolecular Interactions at Interfaces: Case of Supramolecular Tuning of Fullerene's Electronic Structure

AbstractIt is demonstrated that systematic and designated control of supramolecular nanostructures via interfacial engineering enables (opto)electronic C60‐material properties to be widely adjusted. Interestingly, the lowest unoccupied molecular orbital (LUMO) energies of the same amphiphilic fullerene species are tuned up to 120 meV using supramolecular assembly, competitive to complete molecular change; cf. PC61BM to PC71BM causes a change of 200 meV. Morphology control is achieved through different thin‐film production techniques involving molecular assembly at interfaces, including liquid–liquid interfacial precipitation (LLIP), and Langmuir–Blodgett technique at air–water interface. LLIP enables supramolecularly ordered extended surfaces, yielding the least electronically stable LUMO (ELUMO = −4.28 eV). After qualitatively explaining the observed electrochemical LUMO energy variation for these assemblies with varied molecular packing and aggregate dimensions, an analytical equation is proposed, connecting morphological parameters with LUMO energies with prospects in supramolecular chemistry. To demonstrate the applicability of supramolecular structure–electronic property relations and of supramolecular structure fabrication protocols established in this work to tailor device properties, amorphous‐Si/fullerene hybrid solar cells are built and characterized. It is found that the supramolecular structure variation can be successfully translated to the solar cells, giving rise to a prototype linear relation between LUMO energy and open‐circuit voltage.

A dramatic improvement in the tensile strength of fullerene needle-like crystals

Needle-like crystals consisting of a solid solution of C60-C70 fullerene were synthesized by a liquid-liquid interfacial precipitation method using toluene and 2-propanol as solvents. A machined crystal with a V-notch was placed in a focused ion beam scanning electron microscope where it was bent until fracture by pushing it with a molybdenum probe to measure its mechanical properties and its fracture surface was examined. The crystals had a tensile strength of 58-71 MPa, which is much higher than C60 fullerene needle-like crystals and slightly larger than alumina, and a fracture toughness of 1.1-1.3 MPa. Moreover, it is possible to change the plasticity and fracture toughness of the C60-C70 crystals by solvation of different numbers of fullerene molecules. The C60-C70 fullerene crystals have the potential for use as electrodes, anchors for brittle materials, and ductile wires to carry electricity.

Young's Modulus of Fullerene C60-C70 Alloy Crystalline Nanowhiskers.

Crystalline nanowhiskers (NWs) composed of fullerene C60 and C70 molecules, i.e., alloy NWs, were synthesized by a liquid-liquid interfacial precipitation method. The nominal composition of C70 ranged from 0 to 40 mass%. The bending tests of the alloy NWs were performed inside a high-resolution transmission electron microscope, and the deformation behavior was observed in situ. The bending force acting on the NWs were measured simultaneously by an optical deflection method, and the Young's modulus was estimated from the resulting force-flexure curves. The average Young's modulus was found to increase to approximately 30 GPa as the C70 composition was increased to the solubility limit. In contrast, the Young's modulus decreased with increasing NW diameter caused by the addition of C70.

Quasi 2D Mesoporous Carbon Microbelts Derived from Fullerene Crystals as an Electrode Material for Electrochemical Supercapacitors.

Fullerene C60 microbelts were fabricated using the liquid-liquid interfacial precipitation method and converted into quasi 2D mesoporous carbon microbelts by heat treatment at elevated temperatures of 900 and 2000 °C. The carbon microbelts obtained by heat treatment of fullerene C60 microbelts at 900 °C showed excellent electrochemical supercapacitive performance, exhibiting high specific capacitances ca. 360 F g-1 (at 5 mV s-1) and 290 F g-1 (at 1 A g-1) because of the enhanced surface area and the robust mesoporous framework structure. Additionally, the heat-treated carbon microbelt showed good rate performance, retaining 49% of capacitance at a high scan rate of 10 A g-1. The carbon belts exhibit super cyclic stability. Capacity loss was not observed even after 10 000 charge/discharge cycles. These results demonstrate that the quasi 2D mesoporous carbon microbelts derived from a π-electron-rich carbon source, fullerene C60 crystals, could be used as a new candidate material for electrochemical supercapacitor applications.

Synthesis of bipyramidal gold nanoparticle-[C60]fullerene nanowhisker composites and catalytic reduction of 4-nitrophenol

ABSTRACTThe seed solution was prepared by dissolving hydrogen tetrachloroaurate(III) trihydrate (HAuCl4·3H2O), trisodium citrate dihydrate (C6H5Na3O7·2H2O), and sodium borohydride (NaBH4) in distilled water. The resulting reddish-purple seed solution was stirred for 3 h at room temperature. The growth solution was prepared by mixing hydrogen tetrachloroaurate(III) trihydrate (HAuCl4·3H2O), cetyltrimethylammonium bromide (CTAB, (C16H33)N(CH3)3Br), silver nitrate (AgNO3), hydrochloric acid (HCl), and ascorbic acid (C6H8O6) in distilled water. Subsequently, 100 μL of this seed solution was transferred into 10 mL of the growth solution. The mixed solution was maintained at 30 °C for 3 h to obtain a solution of bipyramidal gold nanoparticles. The bipyramidal gold nanoparticle-[C60] fullerene nanowhisker composites were synthesized by applying the liquid-liquid interfacial precipitation (LLIP) method to a saturated solution of C60 in toluene, the solution of bipyramidal gold nanoparticles, and isopropyl alcohol. The prepared bipyramidal gold nanoparticle-[C60] fullerene nanowhisker composites were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The catalytic activity of these composites was confirmed in the reduction of 4-nitrophenol by UV-Vis spectroscopy.

Absorption and Fluorescence Features of an Amphiphilic meso-Pyrimidinylcorrole: Experimental Study and Quantum Chemical Calculations.

Corroles are emerging as an important class of macrocycles with numerous applications because of their peculiar photophysical and metal chelating properties. meso-Pyrimidinylcorroles are easily deprotonated in certain solvents, which changes their absorption and emission spectra as well as their accessible supramolecular structures. To enable control over the formation of supramolecular structures, the dominant corrole species, i.e., the deprotonated form or one of the two NH-tautomers, needs to be identified. Therefore, we focus in the present article on the determination of the UV-vis spectroscopic properties of the free-base NH-tautomers and the deprotonated form of a new amphiphilic meso-pyrimidinylcorrole that can assemble to supramolecular structures at heterointerfaces as utilized in the Langmuir-Blodgett and liquid-liquid interface precipitation techniques. After quantification of the polarities of the free-base NH-tautomers and the deprotonated form by means of quantum chemically derived electrostatic potential distributions at the corroles' van der Waals surfaces, the preferential stabilization of (some of) the considered species in solvents of different polarity is identified by means of absorption spectroscopy. For the solutions with complex mixtures of species, we applied fluorescence excitation spectroscopy to estimate the relative weights of the individual corrole species. This technique might also be applied to identify dominating species in molecularly thin films directly on the subphase' surface of Langmuir-Blodgett troughs. Supported by quantum chemical calculations we were able to differentiate between the spectral signatures of the individual NH-tautomers by means of fluorescence excitation spectroscopy.

Lu2@C82 Nanorods with Enhanced Photoluminescence and Photoelectrochemical Properties.

One-dimensional (1D) single-crystalline hexagonal nanorods of Lu2@C3v(8)-C82 were prepared for the first time using the liquid-liquid interface precipitation (LLIP) method from the interfaces between carbon disulfide (CS2) and isopropyl alcohol (IPA). The length of the nanorods can be readily controlled by varying the concentration of the Lu2@C82 solution in addition to the volume ratio of CS2 to IPA. The latter factor also exhibits a significant influence on the morphology of the crystals. The crystalline structure of the nanorods has been investigated by XRD and selected area electron diffraction (SAED), suggesting a face-centered cubic structure. Photoluminescence of the Lu2@C82 nanorods shows a remarkable enhancement as compared to that of pristine Lu2@C82 powder because of the high crystallinity. Furthermore, we have investigated the photoelectrochemical properties of Lu2@C82 nanorods, proving their potential applications as photodetectors.

Understanding Charge-Transfer Characteristics in Crystalline Nanosheets of Fullerene/(Metallo)porphyrin Cocrystals.

Cocrystals in the form of crystalline nanosheets comprised of C70 and (metallo)porphyrins were prepared by using the liquid-liquid interfacial precipitation (LLIP) method where full control over the morphologies in the C70/(metallo)porphyrins nanosheets has been accomplished by changing the solvent and the relative molar ratio of fullerene to (metallo)porphyrin. Importantly, the synergy of integrating C70 and (metallo)porphyrins as electron acceptors and donors, respectively, into nanosheets is substantiated in the form of a near-infrared charge-transfer absorption. The presence of the latter, as reflection of ground-state electron donor-acceptor interactions in the nanosheets, in which a sizable redistribution of charge density from the electron-donating (metallo)porphyrins to the electron-accepting C70 occurs, leads to a quantitative quenching of the localized (metallo)porphyrin fluorescence. Going beyond the ground-state characterization, excited-state electron donor-acceptor interactions are the preclusion to a full charge transfer featuring formation of a radical ion pair state, that is, the one-electron reduced fullerene and the one-electron oxidized (metallo)porphyrin.

Superstructures with diverse morphologies and highly ordered fullerene C60 arrays from 1 : 1 and 2 : 1 adamantane-C60 hybrid molecules.

Superstructures from fullerene C60-containing compounds, especially those tethered to rigid functional groups with defined shapes, remain largely unexplored. Being the smallest diamondoid, adamantane (Ad) can be viewed as a promising building block for the construction of well-defined superstructures. Here, we report the syntheses of 1 : 1 (4a) and 2 : 1 (4b) Ad-C60 hybrid molecules, which were then used to construct superstructures in binary solvent mixtures via a modified liquid/liquid interfacial precipitation (LLIP) method using CHCl3 as a good solvent. Typically in the combination of DMSO/CHCl3 with a final concentration (cf) of 1.0 mmol L-1, 4a successively forms spheres, plates, nanoflowers and plicated particles with increasing content of DMSO while 4b forms cuboid blocks and microparticles with hierarchically organized surfaces. Changing from DMSO to other poor solvents including acetone, MeOH and EtOAc leads to variations of the morphology of the superstructures for both 4a and 4b. At the nanometer length scale, 4a and 4b adopt different organizations within the superstructures. While 4a tends to self-organize into lamellae with highly ordered C60 layers, the hexagonal phase is dominant in the superstructures formed by 4b. Wettability tests indicate that films formed by the superstructures of 4a and 4b show anti-wetting properties. Besides the solvent effect, the morphology of the superstructures can be also tuned by concentration. For example, when cf is lowered to 0.5 mmol L-1, a new form of superstructure, i.e., fibers, was detected for 4a. Our results also indicate that besides the solvent-induced aggregate transition, gravity-induced sedimentation and subsequent structure ripening can have a significant influence on the final morphology of the superstructures and the aggregate transition pathways.

Optoelectronic properties of one-dimensional fullerene Nanorods

One-dimensional (1D) C60 nanorods were synthesized using a liquid-liquid interfacial precipitation method. TEM and SEM were used to characterize the C60 structure. The C60 nanorod growth direction was mainly limited to the [110] direction. Surface photovoltage spectroscopy (SPS) was used to study the optoelectronic property of 1D C60 nanorods film, and greatly enhanced SPS response was observed compared with the pristine C60 film, indicating that the 1D structure of the C60 nanorods is beneficial for the separation and transport of photo-generated charges. The charge transport property of a single C60 nanorod assembled on Au electrodes was also investigated, and it was found that its I-V curve exhibits special rectifying behavior.

Pressure-induced transformation of ferrocene-doped C<sub>60</sub> nanosheets fabricated by liquid-liquid interfacial precipitation method

Pressure-induced transformation of ferrocene-doped C<sub>60</sub> nanosheets fabricated by liquid-liquid interfacial precipitation method

Preparation of C60 Nanowhiskers-SnO2 Nanocomposites and Photocatalytic Degradation of Organic Dyes.

C60 nanowhiskers were prepared using a liquid-liquid interfacial precipitation (LLIP) method. Tin oxide (SnO2) nanoparticles were synthesized by a reaction of tin (IV) chloride pentahydrate with ammonium nitrate in an electric furnace. The C60 nanowhiskers-SnO2 nanocomposites were calcined in an electric furnace at 700 °C under an inert argon gas atmosphere for 2 h. The crystallinity, morphology and optical properties of the samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and UV-vis spectrophotometry. The photocatalytic activity of the C60 nanowhiskers-SnO2 nanocomposites in the degradation of the organic dyes, such as methylene blue, methyl orange, rhodamine B, and brilliant green, under ultraviolet light at 254 nm by UV-vis spectrophotometry was evaluated and compared with that of C60 nanowhiskers and SnO2 nanoparticles. The experimental results showed that C60 nanowhiskers-SnO2 nanocomposites exhibited remarkably higher photocatalytic degradation of organic dyes compared to C60 nanowhiskers and SnO2 nanoparticles.