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71.
72.
Electron–hole recombination and photocorrosion are two challenges that seriously limit the application of two-dimensional (2D) transition metal dichalcogenides (TMDs) for photocatalytic water splitting. In this work, we propose a 2D van der Waals MoSe2/Ti2CO2 heterojunction that features promising resistance to both electron–hole recombination and photocorrosion existing in TMDs. By means of first-principles calculations, the MoSe2/Ti2CO2 heterojunction is demonstrated to be a direct Z-scheme photocatalyst for overall water splitting with MoSe2 and Ti2CO2 serving as photocatalysts for hydrogen and oxygen evolution reactions, respectively, which is beneficial to electron–hole separation. The ultrafast migration of photo-generated holes from MoSe2 to Ti2CO2 as well as the anti-photocorrosion ability of Ti2CO2 are responsible for photocatalytic stability. This heterojunction is experimentally reachable and exhibits a high solar-to-hydrogen efficiency of 12%. The strategy proposed here paves the way for developing 2D photocatalysts for water splitting with high performance and stability in experiments.The two challenges of electron–hole recombination and photocorrosion for two-dimensional transition metal dichalcogenides in the application of photocatalytic water splitting are simultaneously suppressed by rational design of heterojunctions. 相似文献
73.
针对大口径望远镜光学系统内部空间限制的特点,为了实现失调量校正,提出了一种基于本征系数的失调量解算方法.该方法首先利用波前曲率传感器的原理,通过交替测量前后离焦面的方式采集光斑图.然后,利用无需分区探测的本征函数法进行波前重构,利用本征系数来表征系统波像差,并依据失调量建立灵敏度矩阵模型.最后,根据失调状态与理想状态的本征系数即可求解出失调量.与其他技术途径相比,该方法具有无需添加光学元件、无需分区探测、运算简单的特点.主镜直径为1.8m的望远镜实验结果表明,当次镜偏心距离范围为--0.9~0.9 mm、倾斜角范围为--0.2°~0.2°时,利用本征系数灵敏度矩阵法得到的计算值的误差均小于10%,对大口径望远镜中的应用具有一定的意义. 相似文献
74.
利用模态叠加法建立了水介质微穿孔板的数学模型,基于声电类比法得到其等效电路模型。研究了弹性微穿孔板和弹性背腔对垂直入射吸声系数的影响。与空气介质中的微穿孔板不同,水下微穿孔板因结构阻抗不足,难以取得满意的吸声效果,为此提出了增强型微穿孔吸声结构,并在水介质阻抗管内对理论结果予以验证。结果表明,随着增强型弹性微穿孔板弯曲刚度的增大,其在[20,2000]Hz范围内的平均吸声系数得到提高,逐步趋近于刚性微穿孔板的结果,弹性背板使微穿孔吸声结构的吸声峰向低频移动,低频吸声效果得到提高。 相似文献
75.
76.
Wenjiao Wang Jinlong Zhang Feng Chen Masakazu Anpo Dannong He 《Research on Chemical Intermediates》2010,36(2):163-172
Ag nanoparticles encapsulated by TiO2 shells have the ability to catalyze redox reactions on their surface. By continually monitoring by use of UV–visible spectroscopy
it was found that the surface charge of both TiO2-coated and uncoated colloidal silver particles changed after chemical electron injection. The charging and discharging process
of Ag@TiO2 vary, depending on the different Ag content of the core–shell nanoparticles. In order to enhance the stability of Ag@TiO2 colloids, Fe3+ was doped into the lattice of the TiO2 shells. The experimental results showed that the Fe3+ ions have the capacity to store and transfer electrons. Furthermore, the charging and discharging rate can be controlled
by changing the thickness of the TiO2 shells, because they are limited by the diffusion distance of electrons through the TiO2 shells. 相似文献
77.
N, B, Si-tridoped mesoporous TiO2, together with N-doped, N, B-codoped and N, Si-codoped TiO2, was prepared by a modified sol–gel method. The samples were characterized by wide-angle X-ray diffraction (WAXRD), N2 adsorption–desorption, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, UV–visible
adsorbance spectra (UV–vis) and X-ray photoelectron spectra (XPS). The N, B, Si-tridoped mesoporous TiO2 showed small crystallite size, large specific surface area (350 m2/g), uniform pore distribution (3.2 nm) and strong absorption in the visible light region. The photocatalytic activities of
the samples were evaluated by the photodegradation of 2,4-dichlorophenol (2,4-DCP) aqueous solution. The N, B, Si-tridoping
sample exhibited much higher photocatalytic activity compared with other synthesized photocatalysts. The high activity could
be attributed to the strong absorption in the visible light region, large specific surface area, small crystallite size, large
amount of surface hydroxyl groups, and mesoporosity. 相似文献
78.
Sajjad S Leghari SA Chen F Zhang J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(46):13795-13804
A controllable and reproducible synthesis of highly ordered two-dimensional hexagonal mesoporous, crystalline bismuth-doped TiO(2) nanocomposites with variable Bi ratios is reported here. Analyses by transmission electron microscopy, X-ray diffraction, Raman, and X-ray photoelectron spectroscopy reveal that the well-ordered mesostructure is doped with Bi, which exists as Bi(3+) and Bi((3+x+)). The Bi-doped mesoporous TiO(2) (ms-TiO(2)) samples exhibit improved photocatalytic activities for simultaneous phenol oxidation and chromium reduction in aqueous suspension under visible and UV light over the pure ms-TiO(2), P-25, and conventional Bi-doped titania. The high catalytic activity is due to both the unique structural characteristics and the Bi doping. This new material extends the spectral response from UV to the visible region, and reduces electron-hole recombination, which renders the 2.0% Bi-doped ms-TiO(2) photocatalyst highly responsive to visible light. 相似文献
79.
Cheng CM Mazzeo AD Gong J Martinez AW Phillips ST Jain N Whitesides GM 《Lab on a chip》2010,10(23):3201-3205
This communication describes a simple method for printing aqueous solutions with millimeter-scale patterns on a variety of substrates using an easily fabricated, paper-based microfluidic device (a paper-based "stamp") as a contact printing device. The device is made from inexpensive materials, and it is easily assembled by hand; this method is thus accessible to a wide range of laboratories and budgets. A single device was used to print over 2500 spots in less than three minutes at a density of 16 spots per square centimetre. This method provides a new tool to pattern biochemicals-reagents, antigens, proteins, and DNA-on planar substrates. The accuracy of the volume of fluid delivered in simple paper-to-paper printing is low, and although the pattern transfer is rapid, it is better suited for qualitative than accurate, quantitative work. By patterning the paper to which the transfer occurs using wax printing or an equivalent technique, accuracy increases substantially. 相似文献
80.
Baozhu Tian Zhimang Shao Yunfei Ma Jinlong Zhang Feng Chen 《Journal of Physics and Chemistry of Solids》2011,72(11):1290-1295
B-doped together with Ag-loaded mesoporous TiO2 (Ag/B–TiO2) was prepared by a two-step hydrothermal method in the presence of boric acid, triblock copolymer surfactant, and silver nitrate, followed by heat treatment. The obtained samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption–desorption. It was revealed that all samples consist of highly crystalline anatase with mesoporous structure. For Ag/B–TiO2, B was doped into TiO2 matrix in the form of both interstitial B and substitutional B while Ag was deposited on the surface of B–TiO2 in the form of metallic silver. Compared with the single B-doped or Ag-loaded TiO2 one, mesoporous Ag/B–TiO2 exhibits much higher visible light photocatalytic activity for the degradation of Rhodamine 6G, which can be ascribed to the synergistic effects of B doping and Ag loading by narrowing the band gap of the photocatalyst and preventing the fast recombination of the photogenerated charge carriers, respectively. 相似文献