Papers by Keyword: Nanoporous Carbon

Abstract: ZIF - 8 material has been successfully synthesized through a reaction between zinc nitrate hexahydrate with 2 - metilimidazol in the dimethylformamide solvent in solvotermal condition. Synthesis process is carried out at 120oC for 24 hours . The results show that the characterization by XRD diffractogram synthesized ZIF - 8 has a characteristic peak at 2θ = 7.4^o; 12.7^o; 16.5^o and 18.0^o corresponding to the characteristic peaks of ZIF - 8 standard . The results of ZIF - 8 templated carbon show the XRD pattern of amorphous carbon material, while the carbon activated KOH show peak K₂CO₃ at 2θ = 31.6o. FTIR spectra of synthesized ZIF - 8 has a absorption peak at 420; 760 ; 990 ; 1147 and 1585 cm^-1 which is the characteristic absorption peak of ZIF-8 solids. Then ZIF - 8 characteristic peaks disappear after activated with KOH. Morphology of the ZIF-8 has plumage regular rectangular in shape , and morphology of the resulting carbon particles are also the same rectangular shape with ZIF-8 template.

Abstract: Supercapacitors have been successfully fabricated using nano-sized ZnO/nanoporous carbon (nano-sized ZnO/NPC) electrodes and various hydrogel electrolytes. The nano-sized ZnO/NPC materials have been prepared from zinc acetate (Zn(CH3COO)2) and coconut shell using a simple heating method. Polyvinyl alcohol (PVA) hydrogel blended with phosphoric acid (H3PO4), lithium hydroxide (LiOH) and sodium sulfate (Na2SO4) electrolytes, respectively, has been located between the electrodes. Two of the nano-sized ZnO/NPC electrodes with area of 1 cm2 and those PVA hydrogel electrolytes were pressed together and annealed at 60 °C for 60 min. to construct the supercapacitors. It has been found that the supercapacitor with nano-sized ZnO/NPC electrodes and Na2SO4 electrolyte has the highest capacitance of 60.4 Fg-1.

Abstract: Selective detection of dopamine (DA) in presence of ascorbic (AA) is an important analytical problem, due to its combined existence in the biological system. In the present study, we are reporting an electrochemical detection method for dopamine (DA) in the presence of ascorbic acid (AA) using graphitized nanoporous carbon (NPC) modified glassy carbon electrode (GCE/NPC) in 0.1 M phosphate buffer solution. The modified electrode shows excellent electrocatalytic activities towards the oxidations of DA and AA in neutral pH buffer solution. Compared to unmodified GCE, GCE/NPC shows well separated and enhanced oxidation peak currents. Differential pulse voltammetric technique used as qualitative analytical tool for the detection of DA. The oxidation peak potentials for DA and AA were at -80 and 136 mV vs Ag/AgCl respectively. The modified electrode shows good stability and reproducibility with the relative standard deviation value of 2.6 %. The analytical application of the modified electrode (GCE/NPC) was demonstrated for the individual determination of DA in clinical injection and pharmaceutical tablet by using standard addition method.

Abstract: A novel counter electrode has been fabricated at low temperature using nanoporous carbon (NC) with about 35 nm pore size as based catalysis materials and silver conductor paste (SCP) as connecting adhesive. The efficiency of dye-sensitized solar cells (DSCs) employing this SCP/NC electrode reaches to 5.91%, which is 15% higher than that of DSCs with NC electrode. The improved efficiency is attributed to the enhancement in the fill factor and the short circuit photocurrent density. Electrochemical impedance spectroscopy reveals that all of charge transfer resistance, ohmic serial resistance and Nernst diffusion impedance of SCP/NC electrode decrease compared with NC electrode. Especially, the efficiency of 5.91% is comparable to that of DSCs with Pt electrode.

Abstract: Four nanoporous carbons have been synthesized by using similar silica template method. The structural characterizations showed that the carbons retained ordered hexagonal or cubic pore structure expect for disordered CS41, which was prepared using MCM-41 as template. Nitrogen adsorptions at 77 K revealed that carbons with different pore size distribution, specific surface area and pore volume were obtained. The hydrogen adsorption capacity was measured by volumetric method, and the most promising candidate resulted to be microporous carbon CS41, which exhibited the highest H₂ uptake of 1.17 wt % at 77 K and 1 bar. The capacities of hydrogen adsorbed in the nanoporous carbons were correlated with specific surface area and microporous volume. The result demonstrated that the H₂ uptake in the carbons had essential relationship with volume of pores smaller than 1 nm.

Abstract: In this study, we modified the surface of nanoporous carbons with carboxymethylated polyethyleneimine (CM-PEI) of a high charge density in order to increase the Pt loading on the nanoporous carbons in an aqueous solution. We carried out equilibrium adsorption tests of Pt(IV) on the pure nanoporous carbon and the CM-PEI-coated carbons and evaluated the adsorption isotherm on the CM-PEI-coated carbon using various isotherm models. It was found that the adsorption of Pt(IV) onto the CM-PEI-coated carbons obeys the Langmuir isotherm model.

Abstract: Nanoporous-carbon (NPC) is compared directly to commonly-used polymers as a gassorbing coating material on surface acoustic wave (SAW) microsensor devices. The sensing capability of these materials is measured for volatile organic compounds (VOCs), toxic-industrial chemicals (TICs), and a chemical warfare agents (CWA) simulant. All of the coatings reversibly sorb and desorb the volatile VOC and TIC compounds, however, NPC outperforms the polymers over the range of analyte concentrations studied, especially at the lowest levels, by multiple ordersof- magnitude. Conversely, NPC has good retention properties for the semi-volatile CWA simulant tested, which while detrimental for use on a reversible SAW device, infers that NPC may be wellsuited as a preconcentrator coating for such analytes. NPC is a highly-disordered low-density carbon containing both nanopores and increased interplanar spacing between graphene sheet fragments, self-assembles using pulsed laser deposition, has no residual-stress at room temperature, is stable to 600 °C, and is chemically-inert in harsh environments. It has superior chemical and aging properties compared to the conventional polymer films used in microsensor devices.

Abstract: In this study, a new nanoporous carbon was prepared by anodic oxidation treatment to remove noxic ammonia gas. The acid- and base values of the nanoporous carbon were determined by Boehm’s titration method. And, the surface properties of the carbons were investigated by XPS analysis. Also, N2/77K adsorption isotherm characteristics, including the specific surface areas and nano/micropore volumes were studied by BET and t-plot methods, respectively. The ammonia removal efficiency was confirmed by gas-detecting tube technique. As a result, it was revealed in the case of acidic treatment on nanoporous carbons that the ammonia removal was greatly effective due to the increase of OH groups in carbon surfaces without significant changes of nanostructural properties. It was then found that the acidic anodization of nanoporous carbons was a suitable method for the effective removal of ammonia gas, which could be attributed to the increase of acceptor-donor interactions between acidic oxygen functional groups of carbon adsorbent and basic adsorbate in an adsorbent-adsorbate system.