It has been reported that coupling TiO2 with rare earth upconversion nanocrystals (UCNCs) is an efficient strategy to significantly improve photocatalytic activity of TiO2. However, the rare earth materials are scarcity and cost, and the synthesis process of UCNCs using the rare earth materials is complicated. In the present study, we have designed a new approach using a rare earth-free upconversion nanocrystal (REF-UCNCs) as upconversion luminescent material to replace the rare earth UCNCs. A novel nanocomposite photocatalyst of REF-UCNCs@P25: Mo/GN was developed for the first time. Based on the designed structure, the REF-UCNCs, Mo-doping, and GN (graphene) have a synergistic effect that can improve catalytic activity of P25 significantly. The results of photocatalytic experiments using RhB as a model pollutant under simulated solar light irradiation show that the photocatalytic efficiency of the as-prepared catalyst is 3-folds higher than that of benchmark substance P25. This work provides a new strategy for efficiently improving catalytic activity of semiconductor photocatalysts by coupling with REF-UCNCs. This approach is facile and low-cost which can be widely applied for modification of semiconductor photocatalysts and facilitates their applications in environmental protection issues using solar light.
[Objective] The aim was to study the effects of microwave thawing on aerobic plate count in frozen food.[Method] 3 kinds of frozen food weighted 100,250 and 500 g were thawed at 30% firepower of 700 W microwave oven for 10,20,30,45,60 and 90 s respectively,and the aerobic plate count in samples after and before thawing was counted and compared.[Result] As for frozen fish and shellfish samples weighted 100,250 and 500 g,the thawing time should be controlled at 20,30 and 60 s respectively,and the samples were suitble for cutting after thawing,and there was no effect on the determination of aerobic plate count.As for frozen meat samples weighted 100,250 and 500 g,the thawing time should be controlled at 30,45 and 90 s respectively,and there was no effect on the determination of aerobic plate count after thawing.[Conclusion] As a thawing method with high efficiency,microwave thawing could be used in the frozen food microbiological examination.
Focused on controlling of cost,power consumption,cleanliness and pourability of steelmaking in electric furnace,three process routes to produce low-carbon Si-Al killed steel are compared in this paper.The first process route without LF and RH has the lowest cost(about 70～75 Yuan per ton of steel),its power consumption is about 50~55 KWh,but the cleanliness of steel is poor,w(T.O)35×10-6 ~ 45×10-6,inclusion ≤ 2.0 and ≤1.5 in Class B and Class Ds,respectively.The third process route with RH has the high cost(about 90~100 Yuan per ton of steel),power consumption is about 55~65 KWh,but the cleanliness of steel is better,w(T.O)20×10-6~30×10-6,inclusion ≤1.5 and ≤1.0 in Class B and Class Ds,respectively.
Abstract The intersubband plasmons (ISBPs) of single‐wall carbon nanotubes (SWCNTs) endow SWCNT‐based optoelectronic devices with more functions. However, the structural dependence of the ISBPs of SWCNTs is not fully understood. Here, the effect of electronic types and diameters of SWCNTs on the energy and intensity of their ISBPs is investigated systematically. The results show that the ISBP energy of semiconducting SWCNTs is ≈50–250 meV larger than that of metallic SWCNTs with the same diameters, while the ISBP integral intensity is approximately 1.25 to 4 times stronger. Diameter dependence of ISBPs for both semiconducting and metallic SWCNTs is also observed. With a decrease in diameter, the ISBPs shift to higher energies, while the intensity decreases dramatically. When the diameter is reduced to less than 1 nm, the ISBPs become unobservable. Interestingly, the energy separation between the ISBPs and interband transition S 22 (M 11 ) decreases with an increase in diameter. Theoretical calculations show that the structure‐dependent ISBP characteristics are dominated by the electronic states of SWCNTs. Based on the ISBP characteristics of different SWCNTs, high‐performance SWCNT‐based near‐infrared electrochromic devices are fabricated by mixing small‐diameter metallic SWCNTs with semiconducting SWCNTs due to their high conductivity and negligible ISBP signals.
In this work, energy converters, which contain a GaP–Si heterojunction and Si-based Schottky barrier diodes with Al, Ti, Ag, and W, are used to convert 2 μm-thick 63Ni radioactive source energy into electrical energy. First, energy deposition distributions of the 63Ni radioactive source in these converters are simulated by using the Monte Carlo method. Then, the electrical output properties of the 63Ni/GaP–Si cell and 63Ni/metal–Si cell are determined through the numerical calculation. For the 63Ni/GaP–Si cell, with the optimized thickness of the GaP layer and doping concentration of Si, the maximum output power density and the conversion efficiency are 0.189 µW cm−2 and 1.83%, respectively. For the Si-based Schottky barrier cells with Al, Ti, Ag, and W, the 63Ni/Al–Si cell has the best electrical output properties with the same thickness of the metal layer and doping concentration of Si. When the thickness of metal Al is 0.1 µm and the doping concentration Na is 1 × 1013 cm−3, the maximum output power density and the conversion efficiency are 0.121 µW cm−2 and 1.18%, respectively. The calculation results indicate that the 63Ni/GaP–Si battery has better electrical output properties than the 63Ni/Al–Si Schottky battery. These results are valuable for fabricating practical batteries.
Abstract Multi-physics field (MPF) mechanism to Li dendrite has been broadly used in developed routes of protective Li metal anode. It is proved that dendrite can be optimized by adjusting homogeneity of distributions for charge/thermal/structure through chemical reaction field, concentration field, potential field, heat field etc. However, the accurate quantitative for these distributions is still an unsolved problem. Herein, by the natural of entropy (statistics and thermodynamics), we put forwards a quantitative physics field to describe these distributions, named surface distribution entropy (SDE). Subsequently, coupling it into the MPF of electrochemistry, a new finite element analysis model (MPFCS) is developed, which can quantitatively feedback the effect of surface distribution on dendrite growth. Then we re-understand the relationship between nucleation and Li plating within this entropy involved model. In light of this, a dendrite-suppressing route was accomplished through high-density/low-size nucleation with increasing SDE. A step further, an early-warning method for Li anode was realized via the correlation between SDE and extent of dendrite.
Abstract Fe‐N/C catalysts have currently comparable oxygen reduction reaction (ORR) activity to Pt/C catalysts, which are up for consideration as the most promising non‐precious metal material for research. In spite of this, its development and application are limited by the Fenton effect and insufficient stability. Herein, we have fabricated a FeNi‐nitrogen‐doped porous carbon (FeNi‐NPC) catalyst using solvent thermal method, made from the bimetallic (Fe, Ni)‐doped ZIF‐8. A soft template of glucose was used to control the pore structure and active specific surface area of the catalyst. With the benefit of the electronic effect of the bimetal, FeNi‐NPC catalysts exhibit superior ORR activity and stability to Pt/C catalysts in both acidic ( E 1/2 =0.8672 V) and alkaline ( E 1/2 =0.8663 V) conditions. FeNi‐NPC demonstrated peak power densities in proton exchange membrane fuel cells (PEMFC) of up to 865 mW cm −2 , which exceeds the currently reported M‐N/C catalysts. The work presented here will lead to the design of efficient ORR electrocatalysts in PEMFC devices.
We propose a solar cell structure with periodic units composed by seven α-Si blades and look like a windmill. A 11% absorption enhancement averaged at wavelength range-300nm-800nm can be obtained without any other light-trapping device.
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