The slow photon effect, a structural effect of photonic crystal photocatalyst, is very efficient in the enhancement of photocatalytic reactions. However, slow photons in powdered photonic crystal photocatalyst have ra...
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The slow photon effect, a structural effect of photonic crystal photocatalyst, is very efficient in the enhancement of photocatalytic reactions. However, slow photons in powdered photonic crystal photocatalyst have rarely been discussed because they are usually randomly oriented when the photocatalytic reaction happens in solution under constant stirring. In this work, for the first time we design a gradient ternary TiO 2 -Au-CdS photonic crystal based on three-dimensionally ordered macroporous (3DOM) TiO 2 as skeleton, Au as electron transfer medium and CdS as active material for photocatalytic H 2 production under visible-light. As a result, this gradient ternary photocatalyst is favorable to simultaneously enhance light absorption, extend the light responsive region and reduce the recombination rate of the charge carriers. In particular, we found that slow photons at blue-edge exhibit much higher photocatalytic activity than that at red-edge. The photonic crystal photocatalyst with a macropore size of 250 nm exhibits the highest visible-light H 2 production rate of 3.50 mmolh −1 g −1 due to the slow photon energy at the blue-edge to significantly enhance the incident photons utilization. This work verifies that slow photons at the blue-edge can largely enhance light harvesting and sheds a light on designing the powdered photonic crystal photocatalyst to promote the photocatalytic H 2 production via slow photon effect.
Sodium–selenium (Na–Se) batteries are a promising substitute for traditional Li-ion batteries due to their high theoretical volumetric capacity (∼3260 mA h cm−3). However, shuttle effects and large volume changes s...
Sodium–selenium (Na–Se) batteries are a promising substitute for traditional Li-ion batteries due to their high theoretical volumetric capacity (∼3260 mA h cm−3). However, shuttle effects and large volume changes still limit their practical applications. Herein, we embed Se clusters in nitrogen-doped hierarchically radial-structured microporous carbon (N-HRMC) derived from a zinc-glutamate metal–organic framework (MOF) for advanced sodium storage. In this carbon-based composite, the micropores and the C–Se and C–O–Se bonds in N-HRMC effectively confine the Se clusters and Na2Se during the discharge–charge process. The nitrogen doping in N-HRMC strongly enhances the electrical conductivity of Se and chemical adsorption on Na2Se. In particular, density functional theory (DFT) calculations demonstrate that pyridinic-N atoms provide much more chemical adsorption of Na2Se than graphitic-N and pyrrolic-N atoms. Consequently, the cathode with Se clusters embedded in N-HRMC deliver a capacity of 612 mA h g−1 after 200 cycles at 0.2C, with cycling stability for >500 cycles and a capacity retention of ∼100% from the 20th cycle at 0.5C, representing one of the best reported results for Na–Se batteries. Our work here suggests that embedding Se clusters in nitrogen-doped hierarchically structured microporous carbon systems presents an attractive strategy to enhance the capacity and rate capability of Na–Se batteries.
The high cost and insufficient performance of noble metal-based oxygen reduction reaction(ORR)electrocatalysts in both fuel cells and metal-air batteries is a major barrier for their commercial *** development of inex...
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The high cost and insufficient performance of noble metal-based oxygen reduction reaction(ORR)electrocatalysts in both fuel cells and metal-air batteries is a major barrier for their commercial *** development of inexpensive non-noble metal-based ORR
A multi-field coupled flow-compaction model is developed to simulate the cure process of thick composite laminates manufactured by the autoclave process. The model is verified by comparing the prediction with the expe...
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A multi-field coupled flow-compaction model is developed to simulate the cure process of thick composite laminates manufactured by the autoclave process. The model is verified by comparing the prediction with the experiment result of a thick unidirectional laminate. The results show that the resin flow and compaction start from the top surface and gradually propagates into the interior region, and cease at the gelation point. The non-uniform resin flow causes a gradient distribution of fiber volume fraction in the composite part. A thick cross ply composite laminate model with an interlaminar layer is constructed to analyze the effect of the interlaminar transverse permeability on the flow-compaction behaviour of the thick cross ply composite laminate. The results show that, the thick cross ply composite laminate with high interlaminar transverse permeability has the similar flow-compaction process to the thick unidirectional laminate. An interlaminar layer with low permeability impedes the flow of the resin in the interior of the thick cross ply composite laminate, and causes a slow increasing of fiber volume fraction with curing time comparing with that in a unidirectional laminate.
Monoclinic gallium oxide (β−Ga2O3) has important applications in power devices and deep UV optoelectronic devices because of such novel properties as a wide band gap, high breakdown electric field, and a wide range o...
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Monoclinic gallium oxide (β−Ga2O3) has important applications in power devices and deep UV optoelectronic devices because of such novel properties as a wide band gap, high breakdown electric field, and a wide range of n-type doping conductivity. However, the intrinsic failure mechanisms of β−Ga2O3 remain unknown, which limits the fabrication and packaging of β−Ga2O3-based electronic devices. Here we used density-functional theory at the Perdew-Burke-Ernzerhof level to examine the shear-induced failure mechanisms of β−Ga2O3 along various plausible slip systems. We found that the (001)/〈010〉 slip system has the lowest ideal shear strength of 3.8 GPa among five plausible slip systems, suggesting that (001)/〈010〉 is the most plausible activated slip system. This slip leads to an intrinsic failure mechanism arising from breaking the longest Ga−O bond between octahedral Ga and fourfold-coordinated O. Then we identified the same failure mechanism of β−Ga2O3 under biaxial shear deformation that mimics indentation stress conditions. Finally, the general stacking fault energy (SFE) surface is calculated for the (001) surface from which we concluded that there is no intrinsic stacking fault structure for β−Ga2O3. The deformation modes and SFE calculations are essential to understand the intrinsic mechanical processes of this semiconductor material, which provides insightful guidance for designing high-performance semiconductor devices.
The interaction mechanism and phase evolution of ammonium polyphosphate(APP)mixed with muscovite(APP/muscovite)were studied by TG,XRD and SEM,respectively,during *** the temperature is not higher than 300 ℃,musco...
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The interaction mechanism and phase evolution of ammonium polyphosphate(APP)mixed with muscovite(APP/muscovite)were studied by TG,XRD and SEM,respectively,during *** the temperature is not higher than 300 ℃,muscovite has no effect on the thermaldecomposition of APP,and the initialdecomposition temperature of APP/muscovite at 283 ℃ is basically the same as the APP at 295 ℃,and the main thermaldecomposition products are polyphosphoric acid and NH_4H_2PO_4 at 300 ℃.The polyphosphoric acid,the decomposition products of APP,can enable K and Siout of muscovite and interact with muscovite chemically to generate Al_2O_3·2SiO_2,α-SiO_2 and phosphates(AlPO_4 and K_5P_3O_(10))compounds during 400 ℃-800 ℃,which own obvious adhesive phenomenon and porous structure with the apparent porosity of 58.4%.Further reactions between phosphates other than reactions among Al_2O_3·2SiO_2 and α-SiO_2 can generate KAlP_2O_7 at 1 000 ℃ and the density of residualproduct is improved by low melting point phosphate filling pore to form relatively dense structure and decrease the apparent porosity to 44.4%.The flame resistant and self-supported ceramic materials are expected to enhance the fire-retarding synergistic effect between APP and muscovite.
c-axis-oriented SmBa2Cu3O7(SmBCO) films have been deposited on(100)- LaA1O3(LAO)substrate by metal organic chemical vapor deposition(MOCVD) *** effects of deposition temperature(T(dep)) and total pressure...
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c-axis-oriented SmBa2Cu3O7(SmBCO) films have been deposited on(100)- LaA1O3(LAO)substrate by metal organic chemical vapor deposition(MOCVD) *** effects of deposition temperature(T(dep)) and total pressure(P(tot)) on the orientation and microstructure of SmBCO films were *** orientation of SmBCO films transformed from α-axis to c-axis with increasing of T(dep) from 900 to 1 100℃.At T(dep)=1 050℃,SmBCO films had c-axis orientation and tetragon *** P(tot)^(dep)=400-800 Pa and T(dep)=1 050 ℃,totally c-axis-oriented SmBCO films were *** R(dep) of SmBCO films increased firstly and then decreased with increasing P(tot).The surface of SmBCO films exhibited tetragon morphology at 1 050 ℃ and400 *** thickness of SmBCO film deposited was 1.2μm at P(tot)= 600 Pa,and the corresponding R(dep)was 7.2 μm·h^(-1).
The synthesis of Nd3+,Y3+:CaF2 nanopowder was conducted by azeotropic distillation method,which effectively dehydrated hydrous CaF2 and prevented forming hard agglomerates.X-ray diffraction(XRD),scanning electron...
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The synthesis of Nd3+,Y3+:CaF2 nanopowder was conducted by azeotropic distillation method,which effectively dehydrated hydrous CaF2 and prevented forming hard agglomerates.X-ray diffraction(XRD),scanning electron microscopy(SEM),scanning calorimetries-thermalgravimetry(DSC-TG),Fourier transform infrared spectroscopy(FT-IR) and absorption spectroscopy were performed to characterize the powder *** experimental results showed that products obtained by azeotropic distillation were single phased,rather monodispersed,successfully prevented the hard agglomerate formation and effectively removed the residual water inside the as-prepared precipitate than that of the direct *** absorption spectra showed a wider and stronger absorption bands around 792 nm,which should be profitable for LD pumping.
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