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Application of a photostable silver-assisted Z-scheme NiTiO3 nanorod/g-C3N4 nanocomposite for efficient hydrogen generation
摘要： The performance and reaction mechanism of a silver (Ag)-assisted one-dimensional NiTiO3 nanorod/CN heterostructure nanocomposite (NTACN) photocatalyst for hydrogen (H2) production were explored with simulated sunlight. The physicochemical properties of the synthesized catalysts were examined using various spectrophotometers. The newly developed NTACN samples displayed an enhanced photocatalytic activity in producing hydrogen. Specifically, the H2 production rate of NTACN-5 (with a NT-to-ACN weight ratio of 5) was 3351 mmol/g-h, which was 1.42 times higher than that of ACN-4 with a Ag-to-CN ratio of 4 (2325 mmol/g-h). The effects of the Ag-to-CN and NiTiO3-to-ACN ratios on the photocatalytic activity of NTACN photocatalysts were determined. The NTACN photocatalysts exhibited a high long-term photostability under simulated sunlight irradiation. The increased photocatalyst performance and photostability were primarily ascribed to an improved charge separation efficiency due to a Z-scheme reaction mechanism as well as the assistance provided by Ag as a charge transfer shuttle and in the surface plasmon resonance effect. A photocatalytic mechanism for hydrogen generation over the NTACN photocatalysts under simulated sunlight irradiation is suggested.
关键词： Photostability,Simulated sunlight,One dimension,Z-Scheme mechanism,Charge transfer shuttle
更新于2025-09-09 09:28:46
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[Institution of Engineering and Technology CSAA/IET International Conference on Aircraft Utility Systems (AUS 2018) - Guiyang, China (19-22 June 2018)] CSAA/IET International Conference on Aircraft Utility Systems (AUS 2018) - Design of a Long Stroke Two-axis Compliant Bearing Mechanism for Optical Micro Scanners
摘要： Optical micro-scanners are very important instruments for ultra-high precision imaging and aligning in standing infrared imaging systems. A two-axis optical micro-scanner based on a compliant bearing mechanism is presented for the purpose of realizing large travel range and high resonant frequency. The compliant bearing mechanism is constructed by combining four right angle flexure hinges symmetrically at four corners. The load of the optical micro-scanner is supported by the compliant bearing mechanism, and the two-axis scanning is realized by the two-axis moving coil actuator. The mechanical design of the compliant bearing mechanism is introduced, and the stiffness and travel range of the mechanism are analyzed. A prototype of the optical micro-scanner is fabricated and tested. The experimental results show that the travel range of the scanner is more than 100 μm and the resonant frequency is no less than 100 Hz. The structural size of the designed scanner is within 25×25 mm.
关键词： travel,stiffness,mechanical design,range,compliant bearing mechanism,optical micro-scanner,micro-scanner
更新于2025-09-09 09:28:46
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Pulse dilation gas Cherenkov detector for ultra-fast gamma reaction history at the NIF (invited)
摘要： The Cherenkov mechanism used in Gas Cherenkov Detectors (GCDs) is exceptionally fast. However, the temporal resolution of GCDs, such as the Gamma Reaction History diagnostic at the National Ignition Facility (NIF), has been limited by the current state-of-the-art photomultiplier tube technology to ～100 ps. The soon-to-be deployed Pulse Dilation Photomultiplier Tube (PD-PMT) at NIF will allow for temporal resolution comparable to that of the gas cell or ～10 ps. Enhanced resolution will contribute to the quest for ignition in a crucial way through precision measurements of reaction history and ablator areal density (ρR) history, leading to better constrained models. Features such as onset of alpha heating, shock reverberations, and burn truncation due to dynamically evolving failure modes may become visible for the ?rst time. Test measurements of the PD-PMT at Atomic Weapons Establishment con?rmed that design goals have been met. The PD-PMT provides dilation factors of 2 to 40× in 6 increments. The GCD-3 recently deployed at the NIF has been modi?ed for coupling to a PD-PMT and will soon be making ultrafast measurements.
关键词： Gas Cherenkov Detectors,Pulse Dilation Photomultiplier Tube,National Ignition Facility,temporal resolution,Cherenkov mechanism
更新于2025-09-09 09:28:46
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Photoactivation mechanism, timing of protein secondary structure dynamics and carotenoid translocation in the Orange Carotenoid Protein
摘要： The Orange Carotenoid Protein (OCP) is a two-domain photoactive protein that noncovalently binds an echinenone (ECN) carotenoid and mediates photoprotection in cyanobacteria. In the dark, OCP assumes an orange, inactive state known as OCPO; blue light illumination results in the red active state, known as OCPR. The OCPR state is characterized by large-scale structural changes that involve dissociation and separation of C-terminal and N-terminal domains accompanied by carotenoid translocation into the N-terminal domain. The mechanistic and dynamic-structural relations between photon absorption and formation of the OCPR state have remained largely unknown. Here, we employ a combination of time-resolved UV-visible and (polarized) mid-infrared spectroscopy to assess the electronic and structural dynamics of the carotenoid and the protein secondary structure, from femtoseconds to 0.5 milliseconds. We identify a hereto unidentified carotenoid excited state in OCP, the so-called S* state, which we propose to play a key role in breaking conserved hydrogen-bond interactions between carotenoid and aromatic amino acids in the binding pocket. We arrive at a comprehensive reaction model where the hydrogen-bond rupture with conserved aromatic side chains at the carotenoid β1-ring in picoseconds occurs at a low yield of <1 %, whereby the β1-ring retains a trans configuration with respect to the conjugated π-electron chain. This event initiates structural changes at the N-terminal domain in 1 μs, which allow the carotenoid to translocate into the N-terminal domain in 10 μs. We identified infrared signatures of helical elements that dock on the C-terminal domain β-sheet in the dark and unfold in the light to allow domain separation. These helical elements do not move within the experimental range of 0.5 ms, indicating that domain separation occurs on longer timescales, lagging carotenoid translocation by at least 2 decades of time.
关键词： protein secondary structure dynamics,photoactivation mechanism,Orange Carotenoid Protein,time-resolved spectroscopy,carotenoid translocation
更新于2025-09-09 09:28:46
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Photocatalytic Degradation Mechanism of Reactive Brilliant Blue X-BR by Expanded Perlite/TiO2
摘要： Expanded perlite loaded titanium dioxide photocatalysts were prepared by a sol-gel method. Expanded perlites were modified using H2SO4 and cetyltrimethylammonium bromide in this experiment. The photocatalytic degradation mechanism of Reactive brilliant blue X-BR by expanded perlites loaded titanium dioxide photocatalysts has been investigated. The samples were characterized by scanning electron microscopy, specific surface area, X-ray diffraction analysis. The photocatalytic activities were evaluated by the photocatalytic oxidation of Reactive brilliant blue X-BR solution. It was found that the prepared expanded perlite loaded titanium dioxide photocatalysts have an excellent photocatalytic under ultraviolet illumination. The results of ultraviolet spectrum and infrared absorption spectrum showed that the anthraquinone structures and benzene rings were destroyed under photocatalytic oxidation reaction. The identification by gas chromatography-mass spectrometer analyses indicated that H2O and carbon dioxide could be the primary degradation products.
关键词： Reactive brilliant blue X-BR,Expanded perlites,Photocatalytic degradation mechanism,TiO2
更新于2025-09-09 09:28:46
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Photoluminescence and Growth Mechanism of Oriented Hierarchical Fibrous-Like ZnO Nanowires
摘要： Oriented hierarchical fibrous-like ZnO nanowires with the diameter of about 30–50 nm and the length of about 15–30 um were successfully synthesized on the seed-coated Zn substrates by a simple two-step process. The morphology and structure of the obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It is shown that fibrous-like ZnO nanowires with the aspect ratio of about 500～1000 present the dense reticular structure, which are grown on ZnO nanowire arrays. But beyond that, as-prepared samples are found to be good single crystalline with hexagonal wurtzite structure and preferential grow along the c-axis. A possible growth mechanism of oriented hierarchical fibrous-like ZnO nanowires is presented in detail, revealing that the synthesis of fibrous-like ZnO nanowires should be attributed to differences in the growth rate of the different crystallographic planes and the two growth ways. The photoluminescence (PL) spectra of oriented hierarchical fibrous-like ZnO nanowires grown at 240 min shows the 5 nm blue-shift and enhanced intensity property in the UV emission.
关键词： Hydrothermal Method,Fibrous-Like ZnO Nanowires,Formation Mechanism,Oriented Hierarchical,PL Property
更新于2025-09-04 15:30:14
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Cr(III)-Doped ZnO Nanoflowers: Synthesis, Mechanism and Enhanced Photocatalytic Activity
摘要： ZnO is one of the most widely used photocatalyst, however, because of the wide band gap, its utilization for visible light is unsatisfactory. Therefore, current efforts are directed toward reducing the band gap of ZnO. Transition metal doping has emerged as a promising method, being capable of not only effectively reducing the band gap of ZnO, but inhibiting the recombination of electron–hole pairs. Cr(III)-doped ZnO nano?owers with different Cr/Zn molar ratios were synthesized by a mild, facile and eco-friendly solvothermal process. Subsequently, through various characterizations, it was con?rmed that the dopant Cr(III) entered the lattices of ZnO, substituting the Zn. Owing to the synergy of ?ower-like morphology and Cr(III) dopant, the photocatalytic activity of the products was signi?cantly improved. The optimal Cr/Zn molar ratio was 4%, and the photocatalytic activity of 4% Cr(III)-doped ZnO nano?owers was 1.3 and 3.4 times higher than that of pure ZnO under UV and visible light irradiation, respectively. In addition, the photocatalytic degradation kinetics of methyl orange were also discussed. Furthermore, the mechanism for the improvement in photocatalytic performance of Cr(III)-doped ZnO nano?owers was also investigated based on a series of characterization results such as the UV-vis diffuse re?ectance spectra, photoluminescence, photocurrent and the ?rst-principles calculation.
关键词： Photocatalytic Activity,Mechanism,Nano?owers,Cr-Doped ZnO
更新于2025-09-04 15:30:14
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P-1.11: A Compact Model of Current and Capacitance for Amorphous Indium Gallium Zinc Oxide Thin-Film Transistors
摘要： In recent years, amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) have shown outstanding performance in flexible circuit applications, active matrix display and so on. Therefore, they will play an increasingly important role in the future of electronic applications. At the same time, an analytical model that predicts the electrical characteristics of IGZO TFTs is also critical. In this paper, we present a current and capacitance compact model of a-IGZO TFTs. The compact model can be applied to different channel lengths for a-IGZO TFTs. Besides, it is capable of capturing device characteristics and of maintaining high computational efficiency. Its accuracy is validated through the extensive comparisons between model results and experimental data.
关键词： degenerate mechanism,AC model,Amorphous IGZO thin-film transistors,DC model
更新于2025-09-04 15:30:14
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Microcosmic sulfidization mechanism of S2 on the massicot (1?0?0) surface by DFT study
摘要： The sul?dization mechanism of S2 on the massicot surface was simulated by density function theory (DFT) calculation to illustrate the microscopic reaction mechanism during the surface sul?dization process of lead oxide minerals at high temperature. The calculated results showed that the massicot (1 0 0) surface was the most stable cleavage surface and the main active sites were the O atoms of the surface. The S atoms more easily absorbed on the O atoms of massicot surface in contrast with Pb atoms, leading to the formation of sulfur dioxide in the following reactions. The density of state (DOS) results revealed that O 2p orbital at surface layers of the massicot and S 3p orbital of S2 overlapped ranging from ?0.7 to 0.7 eV, implying that chemical adsorption could occur. The results of Mulliken population suggested that the oxidation and reduction reactions of S atoms from the sul?dization agent were simultaneously involved in the adsorption process. This paper revealed the mechanism of surface sul?dization at an atomic level. It was expected that the study could provide a theoretical reference to improve the sul?dization roasting performance of massicot.
关键词： Microcosmic mechanism,Surface sul?dization,DFT,Massicot,S2
更新于2025-09-04 15:30:14
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Sign-alternating photoconductivity and magnetoresistance oscillations induced by terahertz radiation in HgTe quantum wells
摘要： We report on the observation of terahertz radiation induced photoconductivity and of terahertz analog of the microwave-induced resistance oscillations (MIRO) in HgTe-based quantum well (QW) structures of different width. The MIRO-like effect has been detected in QWs of 20 nm thickness with inverted band structure and a rather low mobility of about 3 × 105 cm2/V s. In a number of other structures with QW widths ranging from 5 to 20 nm and lower mobility we observed an unconventional nonoscillatory photoconductivity signal which changes its sign upon magnetic ?eld increase. This effect was observed in structures characterized by both normal and inverted band ordering, as well as in QWs with critical thickness and linear dispersion. In samples having Hall bar and Corbino geometries an increase of the magnetic ?eld resulted in a single and double change of the sign of the photoresponse, respectively. We show that within the bolometric mechanism of the photoresponse these unusual features imply a nonmonotonic behavior of the transport scattering rate, which should decrease (increase) with temperature for magnetic ?elds below (above) the certain value. This behavior is found to be consistent with the results of dark transport measurements of magnetoresistivity at different sample temperatures. Our experiments demonstrate that photoconductivity is a very sensitive probe of the temperature variations of the transport characteristics, even those that are hardly detectable using standard transport measurements.
关键词： HgTe quantum wells,terahertz radiation,magnetoresistance oscillations,bolometric mechanism,photoconductivity
更新于2025-09-04 15:30:14