다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

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Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

This critical review shows the basis of photocatalytic water splitting and experimental points, and surveys heterogeneous photocatalyst materials for water splitting into H2 and O2, and H2 or O2 evolution from an aqueous solution containing a sacrificial reagent Many oxides consisting of metal cations with d0 and d10 configurations, metal (oxy)sulfide and metal (oxy)nitride photocatalysts have been reported, especially during the latest decade The fruitful photocatalyst library gives important information on factors affecting photocatalytic performances and design of new materials Photocatalytic water splitting and H2 evolution using abundant compounds as electron donors are expected to contribute to construction of a clean and simple system for solar hydrogen production, and a solution of global energy and environmental issues in the future (361 references)

Heterogeneous photocatalyst materials for water splitting

Titanium dioxide/carbon nanotubes (TiO 2 /CNTs) composites were prepared with the aid of ultrasonic irradiation. Products of different TiO 2 :CNTs molar ratio were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) adsorption analysis, thermogravimetric and differential thermal analysis (TGA–DSC), photoluminescence (PL) and UV–vis spectroscopy measurements (UV–vis). The photocatalytic activity was evaluated by the degradation of acetone and by the detection of the hydroxyl radical (·OH) signals using electron paramagnetic resonance (EPR). It is found that the crystalline TiO 2 is composed of both anatase and brookite phases. The agglomerated morphology and the particle size of TiO 2 in the composites change in the presence of CNTs. The CNTs in the composites are virtually all covered by TiO 2 . Other than an increase of the surface area, the addition of CNTs does not affect the mesoporous nature of the TiO 2 . Meanwhile, more hydroxyl groups are available on the surface of the composite than in the case of the pure TiO 2 . The higher the content of CNTs, there is more effective in the suppression of the recombination of photo-generated e − /h + pairs. However, excessive CNTs also shield the TiO 2 from absorbing UV light. The optimal amount of TiO 2 and CNTs is in the range of 1:0.1 and 1:0.2 (feedstock molar ratio). These samples have much more highly photocatalytic activity than P25 and TiO 2 /activated carbon (AC) composite. The mechanism for the enhanced photocatalytic activity of TiO 2 by CNTs is proposed.

Enhancement of photocatalytic activity of mesoporous TiO2 by using carbon nanotubes

Dye-sensitized solar cells (DSSCs) are fabricated based on anatase TiO2 nanosheets (TiO2-NSs) with exposed {001} facets, which were obtained by a simple one-pot hydrothermal route using HF as a morphology controlling agent and Ti(OC4H9)4 as precursor. The prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and N2 adsorption-desorption isotherms. The photoelectric conversion performances of TiO2-NSs solar cells are also compared with TiO2 nanoparticles (TiO2-NPs) and commercial-grade Degussa P25 TiO2 nanoparticle (P25) solar cells at the same film thickness, and their photoelectric conversion efficiencies (η) are 4.56, 4.24 and 3.64%, respectively. The enhanced performance of the TiO2-NS solar cell is due to their good crystallization, high pore volume, large particle size and enhanced light scattering. The prepared TiO2 nanosheet film electrode should also find wide-ranging potential applications in various fields including photocatalysis, catalysis, electrochemistry, separation, purification and so on.

Anatase TiO 2 nanosheets with exposed (001) facets: improved photoelectric conversion efficiency in dye -sensitized solar cells

Graphitic carbon nitride (g-C3N4)-based photocatalysts holds great promise on photocatalytic CO2 conversion into solar fules; however, the efficiency of pristine g-C3N4 is currently limited by its poor visible light absorption and rapid charge recombination. Employing silver chromate (Ag2CrO4) nanoparticles as photosensitizer and graphene oxide (GO) as cocatalyst, a novel ternary Ag2CrO4/g-C3N4/GO composite photocatalyst was fabricated for photocatalytic CO2 reduction into methanol (CH3OH) and methane (CH4). The ternary composites exhibited an enhanced CO2 conversion activity with a turnover frequency of 0.30 h–1, which was 2.3 times that of pristine g-C3N4 under simulated sunlight irradiation. The enhanced photocatalytic activity was due to broadened light absorption, higher CO2 adsorption and more efficient charge separation. Specifically, due to the matched band structure and appropriate loading ratio of Ag2CrO4, a direct Z-scheme Ag2CrO4/g-C3N4 heterojunction is formed, driven by the internal electric field across the Ag2CrO4/g-C3N4 interface. The formation of the direct Z-scheme heterojunction is substantiated by radical scavenging experiments and density functional theory calculations, and it benefits the photocatalytic reaction by accelerating the charge separation and improving the redox ability. Furthermore, GO cocatalyst not only promotes the charge transfer but also provides plentiful CO2 adsorption and catalytic sites. This work exemplifies the facile development of ternary g-C3N4-based photocatalysts with high CO2-conversion activity by coupling a small amount of Ag-based photosensitizer and metal-free cocatalyst.

Ag2CrO4/g-C3N4/graphene oxide ternary nanocomposite Z-scheme photocatalyst with enhanced CO2 reduction activity

Constructing a TiO2 based heterostructure is a very effective strategy for enhancing photocatalytic performance. The details of the electronic structure, interfacial interaction, and photogenerated carrier separation are important for explaining the photocatalytic properties of a heterostructure. Herein, the density of states, charge distribution, and the band offset of the monolayer g-C3N4/TiO2 heterojunction are systematically investigated through the hybrid DFT method. Results indicated that the valence band offset and the conduction band offset of the g-C3N4/TiO2 heterostructure were 0.40 and 0.18 eV, respectively. Interfacial interaction made the TiO2 surface with negative charge, whereas the g-C3N4 surface with positive charge, which led to the formation of a built-in electric field at the interface. Under illumination, the built-in electric field accelerates the transfer of photoexcited electrons in the CB of TiO2 into the VB of g-C3N4, thus resulting in the photoexcited electrons and holes naturally accumulating in the CB of g-C3N4 and the VB of TiO2, respectively. The photoexcited electrons and holes gathering in different surface regions efficiently prolonged the lifetime of photogenerated carriers. Meanwhile, electrons in the CB of g-C3N4 and holes in the VB of TiO2 had a stronger redox ability. Therefore, g-C3N4/TiO2 is a direct Z-scheme photocatalyst, and the Z-scheme heterostructure mechanism can well explain the improved photocatalytic activity of the g-C3N4/TiO2 heterostructure.

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Jiaguo Yu

Papers

Enhancement of photocatalytic activity of mesoporous TiO2 by using carbon nanotubes

Anatase TiO 2 nanosheets with exposed (001) facets: improved photoelectric conversion efficiency in dye -sensitized solar cells

Ag2CrO4/g-C3N4/graphene oxide ternary nanocomposite Z-scheme photocatalyst with enhanced CO2 reduction activity

A new understanding of the photocatalytic mechanism of the direct Z-scheme g-C3N4/TiO2 heterostructure

Ag2O as a new visible-light photocatalyst: self-stability and high photocatalytic activity.