• Bulletin of the Korean Chemical Society
• /
• 제33권2호
• /
• pp.601-607
• /
• 2012

An aspect of organophilic modification for the delamination is described for the layered rare-earth hydroxides in this paper. The interlayer property of $RE_2(OH)_5NO_3{\cdot}nH_2O$, where RE=Eu (LEuH) and Tb (LTbH), was modified by the exchange reaction of nitrate ion with oleate anion that is one of the representative dispersion agents in nonpolar solvents. The bilayer arrangement of long oleate anions in the gallery of $RE_2(OH)_5NO_3{\cdot}nH_2O$ could effectively weaken the stacking of the hydroxide layers. Highly organophilic environment of the interlayer space promoted the introduction of toluene to delaminate the layered structure into their individual sheets. When irradiated with 365 nm UV, the resulting transparent colloidal solutions of toluene containing LEuH and LTbH nanosheets yielded typical red and green emissions, respectively, which are visible to the naked eye.

• Carbon letters
• /
• 제22권
• /
• pp.60-69
• /
• 2017

Nitrogen-doped carbon nanosheets with a developed porous structure were prepared from polyurethane foams by hydrothermal carbonization following $ZnCl_2$ chemical activation. Scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, solid state $^{13}C$ nuclear magnetic resonance (NMR) spectra and X-ray photoelectron spectroscopy were used to characterize the nitrogen-doped carbon nanosheet structure and composition. The removal of Cr(VI) by the N-doped carbon nanosheets was investigated. The results showed that the maximum removal capacity for chromium of 188 mg/g was found at pH=2.0 with PHC-Z-3. pH had an important effect on Cr(VI) removal and the optimal pH was 2.0. Moreover, amino groups and carboxyl groups in the nitrogen-doped carbon nanosheet played important roles in Cr(VI) removal, and promoted the reduction of Cr(VI) to Cr(III).

• Journal of Electrochemical Science and Technology
• /
• 제8권4호
• /
• pp.282-293
• /
• 2017

A new modified carbon paste electrode (CPE) was constructed based on nickel oxide nanoparticles (NiONPs) and graphene nanosheets (Gr) for simultaneous determination of paracetamol (PCM) and mefenamic acid (MFA) in aqueous media and pharmaceutical dosage forms. NiONPs were synthesized via a simple and inexpensive technique and characterized using X-ray diffraction method. Scanning electron microscopy was used for the characterization of the morphology of modified carbon paste electrode (NiONPs/Gr/CPE). Voltammetric studies suggest that the NiONPs and Gr provide a synergistic augmentation that can increase current responses by improvement of electron transfers of these compounds on the NiONPs/Gr/CPE surface. Using cyclic voltammetry, the NiONPs/Gr/CPE showed good sensitivity and selectivity for the determination of PCM and MFA in individually or mixture standard samples in the linear range of $0.1-30{\mu}g\;mL^{-1}$. The resulted limit of detection and limit of quantification were 20 and $60ng\;mL^{-1}$ for PCM, 24 and $72ng\;mL^{-1}$ for MFA, respectively. The analytical performance of the NiONPs/Gr/CPE was evaluated for the determination of PCM and MFA in pharmaceutical dosage forms with satisfactory results.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 춘계학술발표대회
• /
• pp.39.2-39.2
• /
• 2011

With the steady increase in the demand for flexible devices, mainly in display panels, researchers have focused on finding a novel material that have excellent electrical properties even when it is bended or stretched, along with superior mechanical and thermal properties. Graphene, a single-layered two-dimensional carbon lattice, has recently attracted tremendous research interest in this respect. However, the limitations in the growing method of graphene, mainly chemical vapor deposition on transition metal catalysts, has posed severe problems in terms of device integration, due to the laborious transfer process that may damage and contaminate the graphene layer. In addition, to lower the overall cost, a fabrication technique that supports low temperature and low vacuum is required, which is the main reason why solution-based process for graphene layer deposition has become the hot issue. Nonetheless, a direct deposition method of large area, few-layered, and uniform graphene layers has not been reported yet, along with a convenient method of patterning them. Here, we report an evaporation-induced technique for directly depositing few layers of graphene nanosheets with excellent uniformity and thickness controllability on any substrate. The printed graphene nanosheets can be patterned into desired shapes and structures, which can be directly applicable as flexible and transparent electrode. To illustrate such potential, the transport properties and resistivity of the deposited graphene layers have been investigated according to their thickness. The induced internal flow of the graphene solution during tis evaporation allows uniform deposition with which its thickness, and thus resistivity can be tuned by controlling the composition ratio of the solute and solvent.

• Journal of Industrial and Engineering Chemistry
• /
• 제68권
• /
• pp.293-300
• /
• 2018

Reduced graphene oxide (rGO) nanosheets were patterned with poly[benzodithiophene-bis(decyltetradecyl-thien) naphthothiadiazole] (PBDT-DTNT) and poly[bis(triiso-propylsilylethynyl) benzodithiophene-bis(decyltetradecyl-thien) naphthobisthiadiazole] (PBDT-TIPS-DTNT-DT) and used in photovoltaics. Conductive patternings changed via surface modification of rGO; because polymers encountered a high hindrance while assembling onto grafted rGO. The best records were detected in indium tin oxide (ITO):poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS):PBDTDTNT/rGO:PBDT-DTNT:LiF:Al devices, i.e., short current density $(J_{sc})=11.18mA/cm^2$, open circuit voltage $(V_{oc})=0.67V$, fill factor (FF) = 62% and power conversion efficiency (PCE) = 4.64%. PCE increased 2.31 folds after incorporation of PBDT-DTNT into thin films. Larger polymer assemblies on bared-rGO nanosheets resulted in greater phase separations.

• Nano
• /
• 제13권11호
• /
• pp.1850133.1-1850133.9
• /
• 2018

The hexagonal boron nitride nanosheets (BN) were firstly treated by silane coupling agents 3-aminopropyltriethoxysilane (KH550) and 3-glycidoxypropyl-trimethoxysilane (KH560) to introduce some amino and epoxy (EP) groups on the BN surface. These modified BN nanosheets were incorporated into an EP matrix to prepare BN@KH560/EP composites with excellent thermal conductivity and electrical insulation properties. Results showed that the thermal conductivity of BN@KH560/EP composite with 20 vol% BN dosage was found to be 0.442 W/($m{\cdot}K$), which was 81% higher than that of pure EP resin. Both BN/EP composites treated by KH550 and KH560 showed rather good electrical insulation properties, although the dielectric constant of BN@KH550/EP composites were slightly higher than BN@KH560/EP composites. Moreover, BN@KH560/EP composites also showed better thermal and mechanical properties than that of BN@KH550/EP composites.

• 한국표면공학회지
• /
• 제54권3호
• /
• pp.152-157
• /
• 2021

The pseudocapacitor has a high energy density characteristic because it accumulates charges through a paradic redox reaction. However, due to its strong insulation properties, metal hydroxides should be designed as structural systems optimized for charge transfer to support fast electron transport. Also, Nickel material is weak to heat and is easily deformed when used as a cathode material, so stability must be secured. In this study, nickel hydroxide was produced by electrodeposition to secure the stability of nickel. Electrodeposition is a synthetic method suitable for growing optimized nickel hydroxide because it allows fine control. Nickel hydroxide (Ni(OH)₂) is a metal hydroxide used as a pseudocapacitor anode due to its high capacitance, electrical conductivity and resistance. Therefore, in order to determine how Ni(OH)₂ nanosheets are formed and what are the optimization conditions, various measurement methods were used to focus on structural growth of nanosheets produced by electrodeposition.

• 한국표면공학회지
• /
• 제54권1호
• /
• pp.37-42
• /
• 2021

Electrodeposition is a synthetic method that allows fine control of the nucleation and growth factors of metals and is a suitable method for studying the nucleation and growth of Ni(OH)2. Hexa-methylenetetramine (HMT) helps to form Ni(OH)2 nanosheets by increasing the OH- of the nickel precursor solution and helps to improve the electrochemical properties of the electrode. In this study, the structural properties of Ni(OH)2 nanosheets according to the HMT concentration change using electrodeposition were studied. As the concentration of HMT increased, the size and thickness of the Ni(OH)2 nanosheet adsorbed on the surface increased and porosity increased. Also, the Scharifker-Hills nucleation theory model and experimental data were compared. In conclusion, the nanosheet shape of the HMT 7.5 mM sample electrodeposited with -0.85 V vs. Ag/AgCl grew most uniformly, and the best result was obtained as an electrode material for a pseudocapacitor.

• Advances in nano research
• /
• 제16권1호
• /
• pp.81-90
• /
• 2024

In the oil and gas industry, composite materials should exhibit high flexibility and strength for offshore structures. Therefore, weak points in the composites should be improved, such as brittleness, moisture penetration, and diffusion of detrimental ions into nanometric pores. This study aimed to increase the strength, flexibility, and plugging of nanopores using single-layer graphene oxide (SGO) nanosheets. Therefore, SGO is added to unsaturated polyester resin at concentrations of 0.015 and 0.15 % with Normal Methyl Pyrrolidone (NMP) as a solvent for the formation of Nanographene Oxide Reinforced Polymer (NGORP). The mechanical properties of the prepared samples were tested using tensile testing (ASTM-D 638). It has been shown that incorporating SGO, approximately 0.015%, into the base resin resulted in enhanced properties such as rupture resistance forces increased by 745.61 N, applied stress tolerances increased by 4.1 MPa, longitude increased to 1.58 mm, elongation increased by about 2.38%, and rupture energy increased by about 204.51 J. Despite the decrease in tensile force strength properties in the manufactured nanocomposite with 0.15% SGO, it has exclusive flexibility properties such as a high required energy level for rupture of 5,576 times and a formability of 40% more than the base sample. It would be best to use NGORP manufactured from 0.015% nanosheets with exclusive properties rather than base samples for constructing parts and equipment, such as rebars, composite sheets, and transmission pipes, on offshore platforms.

• Carbon letters
• /
• 제19권
• /
• pp.40-46
• /
• 2016

Nitrogen-atom doped graphene oxide was considered to prevent the dissolution of polysulfide and to guarantee the enhanced redox reaction of sulfur for good cycle performance of lithium sulfur cells. In this study, we used urea as a nitrogen source due to its low cost and easy preparation. To find the optimum urea content, we tested three different ratios of urea to graphene oxide. The morphology of the composites was examined by field emission scanning electron microscope. Functional groups and bonding characterization were measured by X-ray photoelectron spectroscopy. Electrochemical properties were characterized by cyclic voltammetry in an organic electrolyte solution. Compared with thermally reduced graphene/sulfur (S) composite, nitrogen-doped graphene/S composites showed higher electroactivity and more stable capacity retention.