(Bin Xu, Toshiro Kaneko, Toshiaki Kato, pp. 517-524)
This cover figure shows an innovative growth method of SWNTs with narrow-chirality distribution, named pulse plasma chemical vapor deposition (CVD). The growth yield of the SWNTs could be improved by repetitive short duration pulse plasma CVD, while maintaining the initial narrow chirality distribution. This study on the precise time-scale incubation dynamics controlling the growth of SWNTs during pulse plasma CVD off [Detail] ...
Since graphene has been discovered, two-dimensional nanomaterials have attracted attention due to their promising tunable electronic properties. The possibility of tailoring electrical conductivity at the atomic level allows creating new prospective 2D structures for energy harvesting and sensing-related applications. In this respect, one of the most successful way to manipulate the physical properties of the aforementioned materials is related to the surface modification techniques employing plasma. Moreover, plasma-gaseous chemical treatment can provide a controlled change in the bandgap, increase sensitivity and significantly improve the structural stability of material to the environment as well. This review deals with recent advances in the modification of 2D carbon nanostructures for novel ‘edge’ electronics using plasma technology and processes.
Plasma catalysis is drawing increasing attention worldwide. Plasma is a partially ionized gas comprising electrons, ions, molecules, radicals, and photons. Integration of catalysis and plasma can enhance catalytic activity and stability. Some thermodynamically unfavorable reactions can easily occur with plasma assistance. Compared to traditional thermal catalysis, plasma reactors can save energy because they can be operated at much lower temperatures or even room temperature. Additionally, the low bulk temperature of cold plasma makes it a good alternative for treatment of temperature-sensitive materials. In this review, we summarize the plasma-assisted reactions involved in dry reforming of methane, CO2 methanation, the methane coupling reaction, and volatile organic compound abatement. Applications of plasma for modification of metal–organic frameworks are discussed.
Pervaporation is an energy-efficient membrane technology for separating liquid molecules of similar physical properties, which may compete or combine with distillation separation technology in a number of applications. With the rapid development of new membrane materials, the pervaporation performance was significantly improved. Fundamental understanding of the mass transport mechanisms is crucial for the rational design of membrane materials and efficient intensification of pervaporation process. Based on the interactions between permeate molecules and membranes, this review focuses on two categories of mass transport mechanisms within pervaporation membranes: physical mechanism (solution-diffusion mechanism, molecular sieving mechanism) and chemical mechanism (facilitated transport mechanism). Furthermore, the optimal integration and evolution of different mass transport mechanisms are briefly introduced. Material selection and relevant applications are highlighted under the guidance of mass transport mechanisms. Finally, the current challenges and future perspectives are tentatively identified.
In this work, we present plasma etching alone as a directed assembly method to both create the nanodot pattern on an etched polymeric (PMMA) film and transfer it to a silicon substrate for the fabrication of silicon nanopillars or cone-like nanostructuring. By using a shield to control sputtering from inside the plasma reactor, the size and shape of the resulting nanodots can be better controlled by varying plasma parameters as the bias power. The effect of the shield on inhibitor deposition on the etched surfaces was investigated by time-of-flight secondary ion mass spectroscopy (ToF-SIMS) measurements. The fabrication of quasi-ordered PMMA nanodots of a diameter of 25 nm and period of 54 nm is demonstrated. Pattern transfer to the silicon substrate using the same plasma reactor was performed in two ways: (a) a mixed fluorine-fluorocarbon-oxygen nanoscale etch plasma process was employed to fabricate silicon nanopillars with a diameter of 25 nm and an aspect ratio of 5.6, which show the same periodicity as the nanodot pattern, and (b) high etch rate cryogenic plasma process was used for pattern transfer. The result is the nanostructuring of Si by high aspect ratio nanotip or nanocone-like features that show excellent antireflective properties.
A pulse plasma chemical vapor deposition (CVD) technique was developed for improving the growth yield of single-walled carbon nanotubes (SWNTs) with a narrow chirality distribution. The growth yield of the SWNTs could be improved by repetitive short duration pulse plasma CVD, while maintaining the initial narrow chirality distribution. Detailed growth dynamics is discussed based on a systematic investigation by changing the pulse parameters. The growth of SWNTs with a narrow chirality distribution could be controlled by the difference in the nucleation time required using catalysts comprising relatively small or large particles as the key factor. The nucleation can be controlled by adjusting the pulse on/off time ratio and the total processing time.
Three-dimensional Prussian blue (PB) nanostructures was obtained via a one-step hydrothermal method. Subsequently, two-dimensional tin disulfide (SnS2) nanosheets were grown onto PB through a facile hydrothermal synthesis. The as prepared SnS2/PB is further employed as the anode of sodium ion batteries (SIBs). SnS2/PB nanoarchitecture delivers a specific capacity of 725.7 mAh∙g−1 at 50 mA∙g−1. When put through more than 200 cycles, it achieved a stable cycling capacity of 400 mAh∙g−1 at 200 mA∙g−1. The stable Na+ storage properties of SnS2/PB was attributed to the synergistic effect among the conductive PB carbon, used as the template in this work. These results obtained potentially paves the way for the development of excellent electrochemical performance with stable performance of SIBs.
In the present study, a plasma-electrochemical method was demonstrated for the synthesis of europium doped ceria nanoparticles. Ce(NO3)3·6H2O and Eu(NO3)3·5H2O were used as the starting materials and being dissolved in the distilled water as the electrolyte solution. The plasma-liquid interaction process was in-situ investigated by an optical emission spectroscopy, and the obtained products were characterized by complementary analytical methods. Results showed that crystalline cubic CeO2:Eu3+ nanoparticles were successfully obtained, with a particle size in the range from 30 to 60 nm. The crystal structure didn’t change during the calcination at a temperature from 400°C to 1000°C, with the average crystallite size being estimated to be 52 nm at 1000°C. Eu3+ ions were shown to be effectively and uniformly doped into the CeO2 lattices. As a result, the obtained nanophosphors emit apparent red color under the UV irradiation, which can be easily observed by naked eye. The photoluminescence spectrum further proves the downshift behavior of the obtained products, where characteristic 5D0→7F1,2,3 transitions of Eu3+ ions had been detected. Due to the simple, flexible and environmental friendly process, this plasma-electrochemical method should have great potential for the synthesis of a series of nanophosphors, especially for bio-application purpose.
The integration of porous organo-silicate low-k materials has met a lot of technical challenges. One of the main issues is plasma-induced damage, occurring for all plasma steps involved during interconnects processing. In the present paper, we focus on porous SiOCH low-k damage mitigation using cryogenic temperature so as to enable micro-capillary condensation. The aim is to protect the porous low-k from plasma-induced damage and keep the k-value of the material unchanged, in order to limit the RC delay of interconnexion levels while shrinking the microchip dimension. The cryogenic temperature is used to condense a gas inside the porous low-k material. Then, the etching process is performed at the temperature of condensation in order to keep the condensate trapped inside the material during the etching. In the first part of this work, the condensation properties of several gases are screened, leading to a down selection of five gases. Then, their stability into the porous structure is evaluated at different temperature. Four of them are used for plasma damage mitigation comparison. Damage mitigation is effective and shows negligible damage for one of the gases at –50°C.
Membranes have attracted much attention as economical methods for industrial chemical processes. The effects of the titanium dioxide nanoparticle load on the morphology and CO2/CH4 separation performance of poly (ether-block-amide) (PEBAX-1657) mixed matrix membranes (MMMs) were investigated from pressures of 3–12 bar and temperatures of 30°C–60°C. The PEBAX membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, atomic force microscopy and tensile strength analysis. The incorporation of TiO2 nanoparticles into the polymeric MMMs improved the CO2/CH4 gas separation performance (both the permeability and selectivity) of the membranes. The CO2 permeability and ideal CO2/CH4 selectivity values of the nanocomposite membrane loaded with 8 wt-% TiO2 were 172.32 Barrer and 24.79, respectively whereas those of the neat membrane were 129.87 Barrer and 21.39, respectively.
Hydroxymethylfurfural (HMF) and furfural are promising chemicals for the creation of a bio-based economy. The development of an inexpensive catalytic system for converting cellulosic biomass into these chemicals is an important step in this regard. Ferric sulphate is a common, cheap and non-toxic Lewis acid that has been used to catalyse reactions such as wood depolymerisation. In this work, ferric sulphate was used to help the production of HMF and furfural from hardwood and softwood pulps. It was found that for hardwood pulp, the use of ferric sulphate alone gave a maximum HMF yield of 31.6 mol-%. The addition of the ionic liquid [BMIM]Cl or HCl as co-catalysts did not lead to an increase in the yields obtained. A prior decationisation step, however, resulted in HMF yields of 50.4 mol-%. Softwood pulp was harder to depolymerise than hardwood, with a yield of 28.7% obtained using ferric sulphate alone. The maximum HMF yield from softwood, 37.9 mol-%, was obtained using a combination of ferric sulphate and dilute HCl. It was thus concluded that ferric sulphate is a promising catalyst for HMF synthesis from cellulosic biomass.
The hierarchical HZSM-5 was prepared via dealumination and desilication of commercial Al-rich HZSM-5, and characterized by X-ray diffraction, 27Al magic-angle spinning nuclear magnetic resonance, inductively coupled plasma mass spectrometry, scanning electron microscope, transmission electron microscope, N2 adsorption-desorption, NH3 temperature-programmed desorption, performed thermogravimetric and Raman spectrum. The results showed that partial framework of HZSM-5 was removed after steam treatment at 0.15 MPa, 500°C for 3 h. HZSM-5 with high specific surface area and much mesoporosity was obtained by the subsequent alkaline treatment. The regulation of acid quantity was achieved by altering the concentration of alkaline. Dealumination and desilication of Al-rich HZSM-5 zeolites became more effective using a combination of steam and alkaline treatments than using alkaline treatment alone. Methanol aromatization reaction was employed to evaluate the catalytic performance of treated HZSM-5 at 0.15 MPa, 450°C and MHSV of 1.5 h−1. The results indicated that after steam treatment, HZSM-5 further treated with 0.2 mol/L NaOH exhibits the best catalytic performance: the selectivity of aromatics reached 42.1% and the lifetime of catalyst attained 212 h, which are much better than untreated HZSM-5.
Glycyrrhetinic acid 3-O-mono-b-D-glucuronide (GAMG), an important pharmaceutical intermediate and functional sweetener, has broad applications in the food and medical industries. A green and cost-effective method for its preparation is highly desired. Using site-directed mutagenesis, we previously obtained a variant of β-glucuronidase from Aspergillus oryzae Li-3 (PGUS1), which can specifically transform glycyrrhizin (GL) into GAMG. In this study, a facile method was established to prepare a CaHPO4-PGUS1 hybrid nanoflower for enzyme immobilization, based on protein-inorganic hybrid self-assembly. Under optimal conditions, 1.2 mg of a CaHPO4-PGUS1 hybrid nanoflower precipitate with 71.2% immobilization efficiency, 35.60 mg·g−1 loading capacity, and 118% relative activity was obtained. Confocal laser scanning microscope and scanning electron microscope results showed that the enzyme was encapsulated in the CaHPO4-PGUS1 hybrid nanoflower. Moreover, the thermostability of the CaHPO4-PGUS1 hybrid nanoflower at 55°C was improved, and its half-life increased by 1.3 folds. Additionally, the CaHPO4-PGUS1 hybrid nanoflower was used for the preparation of GAMG through GL hydrolysis, with the conversion rate of 92% in 8 h, and after eight consecutive runs, it had 60% of its original activity.
Octavinyl polyhedral oligomeric silsesquioxane (POSS) was polymerized on the surface of Fe3O4 nanoparticles (NPs) and then the NPs were functionalized with carboxylic acid groups using thiol-ene click reactions with thioglycolic acid. The as-prepared Fe3O4@POSS-COOH magnetic hybrid NPs had mesoporous structures with an average particle diameter of 15 nm and a relatively high specific surface area of 447 m2∙g−1. Experimental results showed that 4 mg of Fe3O4@POSS-COOH NPs efficiently adsorbed and removed methylene blue from water at 5 min. This is due to the presence of both carboxylic acid and pendant vinyl groups on the Fe3O4@POSS-COOH NPs. These NPs could be easily withdrawn from water within a few seconds under moderate magnetic field and showed high stability in acid and alkaline aqueous mediums.
Fe3O4 nanoparticles immobilized on porous titania in micron-size range were decorated with small-sized gold nanoparticles and used as a plasmonic catalyst for the reduction of 4-nitrophenol. Monodisperse-porous magnetic titania microspheres were synthesized with bimodal pore-size distribution by the sol-gel templating method. Small-sized gold nanoparticles obtained by the Martin method were attached onto the aminated form of the magnetic titania microspheres. A significant enhancement in the catalytic activity was observed using the gold nanoparticle-decorated magnetic titania microspheres compared to gold nanoparticle-decorated magnetic silica microspheres because of the synergistic effect between small-sized gold nanoparticles and titania. The synergistic effect for gold nanoparticle-attached magnetic titania microspheres could be explained by surface plasmon resonance-induced transfer of hot electrons from gold nanoparticles to the conduction band of titania. Using the proposed catalyst, 4-nitrophenol could be converted to 4-aminophenol in an aqueous solution within 0.5 min. The 4-nitrophenol reduction rates were 2.5–79.3 times higher than those obtained with similar plasmonic catalysts. The selection of micron-size, magnetic, and porous titania microspheres as a support material for the immobilization of small-sized gold nanoparticles provided a recoverable plasmonic catalyst with high reduction ability.
Owing to the directional H-bonding, coordination and p-stacking abilities, terpyridines have been widely used as supramolecular tectons in molecular architectures, skeletons in molecular devices and metallopolymers, and are gaining importance in medicinal chemistry. In this paper, we have synthesized, characterized and applied deep eutectic ionic liquids (DEILs) based on 1,4-diazabicyclo[2.2.2]octane; triethylenediamine (DABCO)-derived quaternary ammonium salts for the preparation of terpyridines. These DEILs were synthesized through N-alkylation of DABCO with haloalkanes (1-bromopentane or 1-bromoheptane) followed by mixing and heating with methanol or polyethylene glycol as a hydrogen bond donor. The synthesized DEILs were structurally characterized by IR and NMR. The formation of deep eutectic solvent was confirmed by freezing point depression, it composition was investigated through phase diagram, and its thermal stability was determined through differential scanning calorimetry, derivative thermogravimetry and thermal gravimetric analysis studies. Further, these DEILs were investigated for their effectiveness towards synthesis of 2,2':6',2"-terpyridine, 3,2':6',3"-terpyridineand 4,2':6',4"-terpyridine derivatives through Kröhnke reaction. The results show that these three types of terpyridines can be obtained in reasonable yields (80%-97%) by the one-pot reaction of 2-, 3- or 4-acetylpyridine with a variety of aromatic aldehydes in the presence of DEIL as a reaction medium, sodium hydroxide as a base and ammonium acetate as a cyclizing agent. This methodology is highly efficient and cost-effective for synthesis of symmetrical as well as unsymmetrical terpyridines. Importantly, these DEILs can be reused several times without an obvious loss of activity and are non-toxic, low-volatile, biodegradable and highly thermally stable. Therefore, these DEILs as a non-conventional reaction medium for the synthesis of terpyridines provides appealing opportunities to be investigated in the domain of green synthesis.
Near-infrared spectroscopy mainly reflects the frequency-doubled and total-frequency absorption information of hydrogen-containing groups (O‒H, C‒H, N‒H, S‒H) in organic molecules for near-infrared lights with different wavelengths, so it is applicable to testing of most raw materials and products in the field of petrochemicals. However, the modeling process needs to collect a large number of laboratory analysis data. There are many oil sources in China, and oil properties change frequently. Modeling of each raw material is not only unfeasible but also will affect its engineering application efficiency. In order to achieve rapid modeling of near-infrared spectroscopy and based on historical data of different crude oils under different detection conditions, this paper discusses about the feasibility of the application of transfer learning algorithm and makes it possible that transfer learning can assist in rapid modeling using certain historical data under similar distributions under a small quantity of new data. In consideration of the requirement of transfer learning for certain similarity of different datasets, a transfer learning method based on local similarity feature selection is proposed. The simulation verification of spectral data of 13 crude oils measured by three different probe detection methods is performed. The effectiveness and application scope of the transfer modeling method under different similarity conditions are analyzed.
Understanding the interactions between inorganic nanomaterials and biological species is an important topic for surface and environmental chemistry. In this work, we systematically studied the oocysts of Cryptosporidium parvum as a model protozoan parasite and its interaction with gold nanoparticles (AuNPs) and graphene oxide (GO). The as-prepared citrate-capped AuNPs adsorb strongly on the oocysts leading to a vivid color change. The adsorption of the AuNPs was confirmed by transmission electron microscopy. Heat treatment fully inhibited the color change, indicating a large change of surface chemistry of the oocysts that can be probed by the AuNPs. Adding proteases such as trypsin and proteinase K partially inhibited the color change. DNA-capped AuNPs, on the other hand, could not be adsorbed by the oocysts. GO was found to wrap around the oocysts forming a conformal shell reflecting the shape of the oocysts. Both citrate-capped AuNPs and GO compromised the membrane integrity of the oocysts as indicated by the propidium iodide staining experiment, and they may be potentially used for inactivating the oocysts. This is the first example of using nanomaterials to probe the surface of the oocysts, and it suggests the possibility of using such organisms to template the assembly of nanomaterials.
Evaluation of maximum content of water in natural gas before water condenses out at a given temperature and pressure is the initial step in hydrate risk analysis during pipeline transport of natural gas. The impacts of CO2 and H2S in natural gas on the maximum mole-fractions of water that can be tolerated during pipeline transport without the risk of hydrate nucleation has been studied using our novel thermodynamic scheme. Troll gas from the North Sea is used as a reference case, it contains very negligible amount of CO2 and no H2S. Varying mole-fractions of CO2 and H2S were introduced into the Troll gas, and the effects these inorganic impurities on the water tolerance of the system were evaluated. It is observed that CO2 does not cause any distinguishable impact on water tolerance of the system, but H2S does. Water tolerance decreases with increase in concentration of H2S. The impact of ethane on the system was also investigated. The maximum mole-fraction of water permitted in the gas to ensure prevention of hydrate formation also decreases with increase in the concentration of C2H6 like H2S. H2S has the most impact, it tolerates the least amount of water among the components studied.