Physico-Chemical Property and Catalytic Activity of a CeO2-Doped MnO(x)-TiO2 Catalyst with SO2 Resistance for Low-Temperature NH3-SCR of NO(x).

The effects of CeO2 addition on the catalytic activity and the SO2 resistance of CeO2-doped MnO(x)-TiO2 catalysts were investigated for the low-temperature selective catalytic reduction (SCR) with NH3 of NO(x) emissions in marine applications. The most active catalyst was obtained from 30 wt% CeO2-MnO(x)-TiO2 catalyst in the whole temperature range of 100-300 degrees C at a low gas hourly space velocity (GHSV) of 10,000 h(-)1, and its de-NO(x) efficiency was higher than 90% over 250 degrees C. The enhanced catalytic activity may contribute to the dispersion state and catalytic acidity on the catalyst surface, and the highly dispersed Mn and Ce on the nano-scaled TiO2 catalyst affects the increase of Lewis and Brønsted acid sites. A CeO2-rich additive on MnO(x)-TiO2 could provide stronger catalytic acid sites, associated with NH3 adsorption and the SCR performance. As the results of sulfur resistance in flue gas that contains SO2, the de-NO(x) efficiency of MnO(x)-TiO2 decreased by 15% over 200 degrees C, whereas that of 30 wt% ceria-doped catalyst increased by 14-21% over 150 degrees C. The high SO2 resistance of CeO2-MnO(x)-TiO2 catalysts that resulted from the addition of ceria suppressed the formation of Mn sulfate species, which led to deactivation on the surface of nano-catalyst.

Heterogeneous Decomposition of Volatile Organic Compounds by Visible-Light Activated N, C, S-Embedded Titania.

In this study, a N-, C-, and S-doped titania (NCS-TiO2) composite was prepared by combining the titanium precursor with a single dopant source, and the photocatalytic activity of this system for the decomposition of volatile organic compounds (VOCs) at indoor-concentration levels, under exposure to visible light, was examined. The NCS-TiO2 composite and the pure TiO2 photocatalyst, used as a reference, were characterized via X-ray diffraction, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The average efficiencies of benzene, toluene, ethyl benzene, and o-xylene decomposition using NCS-TiO2 for were 70, 87, -100, and -100%, respectively, whereas the values obtained using the pure TiO2 powder were -0, 18, 49, and 51%, respectively. These results suggested that, for the photocatalytic decomposition of toxic VOCs under visible-light exposure conditions, NCS-TiO2 was superior to the reference photocatalyst. The decomposition efficiencies of the target VOCs were inversely related to the initial concentration and relative humidity as well as to the air-flow rate. The decomposition efficiencies of the target chemicals achieved with a conventional lamp/NCS-TiO2 system were higher than those achieved with a light emitting diode/NCS-TiO2 system. Overall, NCS-TiO2 can be used for the efficient decomposition of VOCs under visible-light exposure, if the operational conditions are optimized.

Very Smooth Ultrananocrystalline Diamond Film Growth by a Novel Pretreatment Technique.

Very smooth ultrananocrystalline diamond (UNCD) film growth on SiC substrate was achieved by a novel pretreatment technique consisted of SiC surface texturing and deaggregation of nanodiamond (ND) seed particles. Texturing of SiC surfaces in Ar and SF6/02 plasmas was found to be able to provide normalized roughness values of 0.5-7.0 compared to the untreated surface. SiC surface plasma-textured and seeded with H2 heat-treated ND particles at 600 degrees C showed the highest nucleation density of ~44.2 x 10(11) cm(-2) and a highly uniform coverage of surface with very fine ND seeds. The UNCD film grown with this new pretreatment technique showed a very smooth surface morphology consisted of small and uniformly distributed grains.

The Role of Magnesium Ion Substituted Biphasic Calcium Phosphate Spherical Micro-Scaffolds in Osteogenic Differentiation of Human Adipose Tissue-Derived Mesenchymal Stem Cells.

This study was investigated the role of magnesium (Mg2+) ion substituted biphasic calcium phosphate (Mg-BCP) spherical micro-scaffolds in osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells (hAT-MSCs). Mg-BCP micro-scaffolds with spherical morphology were successfully prepared using in situ co-precipitation and spray drying atomization process. The in vitro cell proliferation and differentiation of hAT-MSCs were determined up to day 14. After in vitro biological tests, Mg-BCP micro-scaffolds with hAT-MSCs showed more enhanced osteogenicity than pure hAT-MSCs as control group by unique biodegradation of TCP phase and influence of substituted Mg2+ ion in biphasic nanostructure. Therefore, these results suggest that Mg-BCP micro-scaffolds promote osteogenic differentiation of hAT-MSCs.

Iron-functionalized titanium dioxide on flexible glass fibers for photocatalysis of benzene, toluene, ethylbenzene, and o-xylene (BTEX) under visible- or ultraviolet-light irradiation.

UNLABELLED: Iron-functionalized titanium dioxide (TiO2) composites with various Fe-to-Ti ratios were prepared on flexible glass fibers (GF-Fe-TiO2) via a sol-gel method, followed by a dip-coating process. The photocatalytic ability of these composites in degrading selected volatile organic compounds (VOCs; benzene, toluene, ethylbenzene, and o-xylene [BTEX]) at indoor concentration levels was examined. The GF-Fe-TiO2 composites were characterized using scanning electron microscopy, energy-dispersive X-ray elemental analysis, ultraviolet (UV)-visible spectroscopy, and X-ray diffraction. The GF-Fe-TiO2 composites showed superior photocatalytic performance to that of a reference glass fiber-supported TiO2 photocatalyst for the treatment of BTEX under visible light. However, this trend was reversed under UV irradiation. Specifically, the average BTEX photocatalytic efficiencies of the 0.01-GF-Fe-TiO2 composite in a 3-hr visible-light photocatalytic process were 4%, 33%, 51%, and 74%, respectively. Conversely, the average BTEX photocatalytic efficiencies obtained for GF-TiO2 were close to 0%, 5%, 16%, and 29%, respectively. These findings demonstrated that the GF-Fe-TiO2 composites could be applied to photocatalytically purify BTEX, especially under visible-light exposure. Moreover, the GF-Fe-TiO2 composites prepared with different Fe-to-Ti ratios displayed different BTEX photocatalytic decomposition efficiencies under visible or UV light, allowing for optimization of the Fe-to-Ti ratio (which was found to be 0.01). IMPLICATIONS: The application of nanomaterials for air purification necessitates a supporting material to stabilize them while in contact with the treated air in the photocatalytic chamber. Glass fibers have an obvious advantage over other supporting materials mainly because of its flexibility, which makes it much easier to handle. However, the applications of glass fiber-supported, visible light-activated photocatalysts to the treatment of air pollutants are rarely reported in literature. Accordingly, this study aimed to investigate the applicability of glass fiber-supported Fe-TiO2 for the purification of VOCs under visible- as well as UV-light exposure.

Multi-year evaluation of ambient volatile organic compounds: temporal variation, ozone formation, meteorological parameters, and sources.

The multi-year characteristics of ambient volatile organic compounds (VOCs) and their source contribution in a selected metropolitan (Seoul) and rural (Seokmolee) areas in Korea were investigated to provide the framework for development and implementation of ambient VOC control strategies. For Seoul, none of the three VOC groups exhibited any significant trend in their ambient concentrations, whereas for Seokmolee, they all showed a generally decreasing trend between 2005 and 2008 and an increasing trend after 2008. Two paraffinic (ethane and propane) and two olefin (ethylene and propylene) hydrocarbons displayed higher concentrations during the cold season than warm season, while the other target VOCs did not exhibit any significant trends. Ethylene and toluene were the first and second largest contributors to ozone formation, respectively, whereas several other VOCs displayed photochemical ozone formation potential values less than 0.01 ppb. For both areas, there was a significant negative correlation between ambient temperature and the selected VOC group concentrations. In contrast, a significant positive correlation was observed between relative humidity and the three VOC group concentrations, while no significant correlation was observed between wind speed and VOC group concentrations. For Seoul, the combination of vehicle exhaust and gasoline/solvent evaporation was the greatest source of VOCs, followed by liquid natural gas (LNG) and liquid petroleum gas (LPG). However, combination of LNG and LPG was the greatest source of VOCs at Seokmolee, followed by the combination of vehicle exhaust and gasoline evaporation, and then biogenic sources.

Anti-Biofouling Effect of PEG-Grafted Block Copolymer Synthesized by RAFT Polymerization.

Poly(glycidyl methadrylate-block-styrene) (PGMA-b-PS), a block copolymer consisting of glycidyl methacrylate and styrene, was synthesized via reversible addition-fragmentation chain transfer living polymerization. The synthesized PGMA-b-PS was then grafted with low-molecular-weight polyethylene glycol (PEG) via epoxy ring opening to give PGMA-g-PEG-b-PS, which was evaluated as an anti-biofouling coating material. As a preliminary test for the anti-biofouling effect, a protein adsorption experiment was performed on the synthesized block copolymer surface. The block copolymers were spin-coated onto silicon wafers, and protein adsorption experiments were carried out using fluorescein isothiocyanate conjugate-labeled bovine serum albumin. The fluorescence intensity of the protein adsorbed on the block copolymer surface was compared with that of a polystyrene film as a reference. The synthesized PGMA-g-PEG-b-PS film showed much lower fluorescence intensity than that of the PS film.

Degradation of gas-phase organic contaminants via nitrogen-embedded one-dimensional rod-shaped titania in a plug-flow reactor.

In this study, one-dimensional rod-shaped titania (RST) and nitrogen-doped RST (N-RST) with different ratios of N to Ti were prepared using a hydrothermal method and their applications for purification of indoor toxic organic contaminants in a plug-flow reactor were examined under visible or ultraviolet (UV) irradiation. The surface characteristics of as-prepared photocatalysts were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-visible spectroscopy. The TEM images revealed that both pure RSTs and N-RSTs displayed uniform and nanorod-shaped structures. XRD revealed that the photocatalysts had crystalline TiO2. The UV-visible spectra demonstrated that the N-RSTs could be activated in the visible region. In most cases, N-RSTs showed higher degradation efficiencies than pure RSTs under visible-light and UV irradiation. N-RSTs with a N-to-Ti ratio of 0.5 exhibited the highest degradation efficiencies of benzene, toluene, ethyl benzene, and o-xylene (BTEX), suggesting the presence of an optimal N-to-Ti ratio for preparation of N-RSTs. In addition, the average degradation efficiencies of BTEX determined for the N-RSTs with a N-to-Ti ratio of 0.5 under visible-light irradiation for the lowest initial concentration (IC, 0.1 ppm) were 19%, 53%, 85%, and 92%, respectively, while the degradation efficiencies for the highest IC (2.0 ppm) were 2%, 8%, 17%, and 33%. These values decreased as the stream flow rate increased. Overall, the as-prepared N-RSTs could be effectively applied for degradation of toxic gas-phase organic contaminants under visible-light as well as UV irradiation.

Synthesis and properties of new low band gap semiconducting polymers.

Low band gap organic semiconducting polymers were prepared as p-type donors for organic photovoltaic devices. A novel dibrominated monomer composed of phenothiazine, thiophene, and benzothiadiazole (DPDTBT) was synthesized as a low band gap core block. DPDTBT was copolymerized with three different boronic esters of dithiophene, fluorene, and phenothiazine by the Suzuki coupling polycondensation reaction. The band gap energies of the synthesized polymers ranged between 2.05 and 2.11 eV, depending on the polymer structure. Bulk heterojunction solar cells fabricated using the polymers and [6,6]-phenyl C71-butyric acid methyl ester (PC70BM) as an acceptor were characterized. The best power conversion efficiency obtained from the fabricated devices under simulated AM 1.5 G solar irradiation of 100 mW/cm2 was 0.46%.

Stabilization of oxygen-deficient structure for conducting Li4Ti5O12-δ by molybdenum doping in a reducing atmosphere.

Li4Ti5O12 (LTO) is recognized as being one of the most promising anode materials for high power Li ion batteries; however, its insulating nature is a major drawback. In recent years, a simple thermal treatment carried out in a reducing atmosphere has been shown to generate oxygen vacancies (VO) for increasing the electronic conductivity of this material. Such structural defects, however, lead to re-oxidization over time, causing serious deterioration in anode performance. Herein, we report a unique approach to increasing the electronic conductivity with simultaneous improvement in structural stability. Doping of LTO with Mo in a reducing atmosphere resulted in extra charges at Ti sites caused by charge compensation by the homogeneously distributed Mo(6+) ions, being delocalized over the entire lattice, with fewer oxygen vacancies (VO) generated. Using this simple method, a marked increase in electronic conductivity was achieved, in addition to an extremely high rate capability, with no performance deterioration over time.

Characteristics of atmospheric visibility and its relationship with air pollution in Korea.

Although analysis of long-term data is necessary to obtain reliable information on characteristics of atmospheric visibility and its relationship with air pollution, it has rarely been performed. Therefore, a long-term evaluation of atmospheric visibility in characteristically different Korean cities, as well as a remote island, during 2001 to 2009, was performed in this study. In general, visibility decreased in the studied areas during the 9-yr study period. In addition, all areas displayed a distinct seasonal trend, with high visibility in the cold season relative to the warm season. Weekday visibility, however, did not significantly differ from weekend visibility. Similarly, the number of days per year for both low (<10 km) and high visibility (>19 km) fluctuated during the study period. Busan (a coastal city) exhibited the highest visibility, with an overall average of 17.6 km, followed by Daegu (a basin city), Ulsan (with concentrated petrochemical industries), Ullungdo (a remote island), and Seoul (the capital of Korea). Visibility was found to be significantly correlated with target air pollutants, except for ozone, for all metropolitan cities, whereas it was significantly correlated only with particulate matter with an aerodynamic diameter <10 µm (PM10) and ozone on the remote island (Ullungdo). Among the metropolitan cities, Seoul exhibited the lowest visibility for both the PM10 standard exceedance and non-exceedance days, followed by Ulsan, Daegu, and Busan. The results of this study can be used to establish effective strategies for improving urban visibility and air quality.

Enhanced Photocatalytic Efficiency of N-F-Co-Embedded Titania under Visible Light Exposure for Removal of Indoor-Level Pollutants.

N-F-co-embedded titania (N-F-TiO2) photocatalysts with varying N:F ratios were synthesized and tested for their ability to photocatalyze the degradation of pollutants present at indoor air levels using visible light. The synthesis was achieved using a solvothermal process with tetrabutyl titanate, urea and ammonium fluoride as sources of Ti, N and F, respectively. Three selected volatile organic compounds (toluene, ethyl benzene and o-xylene) were selected as the test pollutants. The prepared composites were characterized using X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and Ultra-violet (UV)-visible spectroscopy. The photocatalytic degradation efficiencies of N-F-TiO2 composites were higher than those obtained using pure TiO2 and N-TiO2. Moreover, these efficiencies increased as the N:F ratio decreased from sixteen to eight, then decreased as it dropped further to three, indicating the presence of an optimal N:F ratio. Meanwhile, as retention time decreased from 12.4 to 0.62 s, the average photocatalytic efficiencies decreased from 65.4% to 21.7%, 91.5% to 37.8% and 95.8% to 44.7% for toluene, ethyl benzene and o-xylene, respectively. In contrast, the photocatalytic reaction rates increased as retention time decreased. In consideration of all of these factors, under optimized operational conditions, the prepared N-F-TiO2 composites could be utilized for the degradation of target pollutants at indoor air levels using visible light.

Titania Nanotubes Grown on Carbon Fibers for Photocatalytic Decomposition of Gas-Phase Aromatic Pollutants.

This study aimed to prepare titania (TiO2) nanotube (TNT) arrays grown on un-activated carbon fibers (UCFs), with the application of different TiO2 loadings based on the coating-hydrothermal process, and to evaluate their photocatalytic activity for the degradation of sub-ppm levels of aromatic pollutants (benzene, toluene, ethyl benzene, and o-xylene (BTEX)) using a plug-flow photocatalytic reactor. The characteristics of the prepared photocatalysts were determined by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), UV-visible absorption spectroscopy (UV-Vis) and X-ray diffraction (XRD) analyses. Spectral analysis showed that the prepared photocatalysts were closely associated with the characteristics of one-dimensional nanostructured TiO2 nanotubes for TNTUCFs and spherical shapes for TiO2-coated UCF (TUCF). The photocatalytic activities of BTEX obtained from TNTUCFs were higher than those obtained from a reference photocatalyst, TUCF). Specifically, the average degradation efficiencies of BTEX observed for TNTUCF-10 were 81%, 97%, 99%, and 99%, respectively, while those observed for TUCF were 14%, 42%, 52%, and 79%, respectively. Moreover, the photocatalytic activities obtained for TNTUCFs suggested that the degradation efficiencies of BTEX varied with changes in TiO2 loadings, allowing for the optimization of TiO2 loading. Another important finding was that input concentrations and air flow rates could be important parameters for the treatment of BTEX, which should be considered for the optimization of TNTUCFs application. Taken together, TNTUCFs can be applied to effectively degrade sub-ppm levels of gas-phase aromatic pollutants through the optimization of operational conditions.

Enhanced gas sensing performance of hydrophilic graphite nanoparticles synthesized by liquid phase pulsed laser ablation.

In this study, we firstly report that hydrophilic graphite nanoparticles were successfully synthesized by liquid phase pulsed laser ablation method and the carbon-polymer composite sensor prepared with the nanoparticles showed a markedly enhanced gas sensing performance. The pulsed laser ablation of graphite rod in water generated well dispersed hydrophilic graphite nanoparticle and they showed an extremely high stability in water without any surfactant or stabilizer. FT-IR spectra showed that the hydrophilic functional groups such as carboxyl and carbonyl groups were simultaneously introduced onto the surface of graphite with the nanoparticle formation and the highly negative zeta potential due to the functional groups was the origin of the markedly high stability in water. Finally, the carbon-polymer composite sensor composed of hydrophilic graphite nanoparticles and polyvinylpyrrolidone (PVP) demonstrated an enhanced detection response in comparison with the commercial carbon black, and which was attributed to the introduced hydrophilic functional groups on graphite nanoparticle surfaces.

Blister packing of copper hydroxide and titania nanoparticles on graphene and its recycling.

Metal nanoparticles anchored on a graphene substrate find many applications such as sensors, catalysts, lithium ion batteries, etc. However, to date, graphene-metal nanohybrids have been synthesized by either covalent or ionic interactions between the graphene substrate and the metal nanoparticles. In this manuscript, we report a green and facile method to "bubble pack" metal nanoparticles on a graphene substrate by a simple process utilizing eco-friendly ionic liquids in conjunction with microwave heating. Copper nanoparticles bubble packed on graphene showed enhanced glucose sensing when compared to covalently bonded copper/graphene hybrids. Titania nanoparticles bubble packed on graphene when applied as anode materials in lithium ion batteries exhibited two times more lithium ion retention when compared to covalently bonded titania/graphene hybrids. "End of life" disposal of nanomaterials into the environment is a growing area of concern in recent days. One way of dealing with this problem is to extend the life cycle of nanomaterials by reusing the nanomaterials in multiple applications. In this report, we also show the recyclability of our novel bubble packaging material, by etching out the metal nanoparticles resulting in a unique 3D hierarchical graphene nanocup decorated graphene. The applicability of this recycled material in super capacitors is also reported.

Free standing acetylene black mesh to capture dissolved polysulfide in lithium sulfur batteries.

Herein, we report a cheap and simple approach to solve the polysulfide dissolution problem in lithium sulfur batteries. It was interestingly revealed that a simple insertion of acetylene black mesh enabled us to obtain the capacity of 1491 mA h g(-1) at initial discharge and 1062 mA h g(-1) after 50 cycles.