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101.
The development of highly active and stable reversible oxygen electrocatalysts is crucial for improving the efficiency of metal-air battery devices. Herein, an efficient liquid exfoliation strategy was designed for producing silk-like FeS2/NiS2 hybrid nanocrystals with enhanced reversible oxygen catalytic performance that displayed excellent properties for Zn-air batteries. Because of the unique silk-like morphology and interface nanocrystal structure, they can catalyze the oxygen evolution reaction (OER) efficiently with a low overpotential of 233 mV at j = 10 mA cm?2. This is an improvement from the recently reported catalysts in 1.0 M KOH. Meanwhile, the oxygen reduction reaction (ORR) activity of the silk-like FeS2/NiS2 hybrid nanocrystals showed an onset potential of 911 mV and a half-wave potential of 640 mV. In addition, the reversible oxygen electrode activity of the silk-like FeS2/NiS2 hybrid nanocrystals was calculated to be 0.823 V, based on the potential of the OER and ORR. Further, the homemade rechargeable Zn-air batteries using FeS2/NiS2 hybrid nanocrystals as the air-cathode displayed a high open-circuit voltage of 1.25 V for more than 17 h and an excellent rechargeable performance for 25 h. The solid Zn-air batteries exhibited an excellent rechargeable performance for 15 h. This study provided a new method for designing interface nanocrystals with a unique morphology for efficient multifunctional electrocatalysts in electrochemical reactions and renewable energy devices. 相似文献
102.
Recent developments in quantitative surface analysis by Auger (AES) and x-ray photoelectron (XPS) spectroscopies are reviewed and problems relating to a more accurate quantitative interpretation of AES/XPS experimental data are discussed. Special attention is paid to consideration of elementary physical processes involved and influence of multiple scattering effects on signal line intensities. In particular, the major features of core-shell ionization by electron impact, Auger transitions and photoionization are considered qualitatively and rigorous approaches used to calculate the respective transition probabilities are analysed. It is shown that, in amorphous and polycrystalline targets, incoherent scattering of primary and signal Auger and photoelectrons can be described by solving analytically a kinetic equation with appropriate boundary conditions. The analytical results for the angular and energy distribution, the mean escape depth, and the escape probability as a function of depth of origin of signal electrons as well as that for the backscattering factor in AES are in good agreement with the corresponding Mote Carlo simulation data. Methods for inelastic background subtraction, surface composition determination and depth-profile reconstructions by angle-resolved AES/XPS are discussed. Examples of novel techniques based on x-ray induced photoemission are considered. 相似文献
103.
Yoshiharu Yamane Yozo Nakamura Hiroyuki Okamoto Hiroshi Ooshima Jyoji Kato 《Applied biochemistry and biotechnology》1995,50(3):317-322
Effects of pH and dissolved oxygen concentration on batchwise riboflavin production by a 5-fluorouracil (5-FU)-resistant mutant
ofArthrobacter sp. were investigated. The reaction was carried out in a jar fermentor. The optimal pH of culture medium was around 7.3.
Dissolved oxygen concentration was almost constant during fermentation at 600 rpm of agitation rate. Production of riboflavin
reached a maximum of 160 mg/L after 70 h fermentation under the agitation rate of 600 rpm, aeration rate of 1.0 L/min, and
pH 7.0. 相似文献
104.
G. Gousset M. Touzeau M. Vialle C. M. Ferreira 《Plasma Chemistry and Plasma Processing》1989,9(2):189-206
A simple kinetic model predicting the concentration of oxygen atoms, metastable singlet molecules O2(a
1) and negative ions O — in the positive column of a DC glow discharge is developed. The calculated O and O2(a
1) concentrations are compared to previously reported measurements for pressuresp=0.2–2 Torr and discharge currentsI=10–80 mA. The electron density calculated from the continuity equationj=n
e
e v
d agrees well with experiment. The rate coefficients for electron impact processes used in the balance equations of O, O2(a
1), and O– were taken from the literature as a function of the reduced electric fieldE/N forE/N=40–80 Td. A reasonable agreement is obtained between the model and the experiment with a set of 10 reactions for the production and destruction of the above-mentioned species 相似文献
105.
Flow injection spectrofluorimetry with in-line Winklers procedure was developed for the dissolved oxygen (DO) determination. 2-Thionaphthol reacted with iodine produced by Winkler’s method to form fluorescence inactive disulfide compound. To automate the process completely, a 5-channel flow system with a newly designed 16-way valve was assembled. The system consisted of a dispersion coil (DC), a precipitate formation coil (PFC), a precipitate dissolving coil (PDC), and extraction coil (EC). A calibration can be constructed by using a standard iodine solution for dissolved oxygen. The calibration graph was linear over the range 1.2×10−4∼6.0×10−4 mol l−1 iodine (1.96∼9.80 mg O l−1)). The relative standard deviation (n=6) was below 0.3% for the 4×10−4 mol l−1 iodine (6.27 mg O l−1) determination. The sample throughput was 12/h. 相似文献
106.
QIN Jun XIE Ming-Gui JIANG Qing ZHAO Hua-Ming Department of Chemistry Sichuan University Chengdu Sichuan ChinaLIU Sheng-Chong Analytical Testing Center Sichuan University Chengdu Sichuan ChinaTAO Chang-Yuan Department of Chemistry Chongqing University Chongqing Sichuan China 《中国化学》1995,13(1):1-9
In view of the nature of orderness in structure and the mesomorphism in property of liquid crystal, the function of which is further exploited by integrating it with the feature of crown ether. The monoarmed crown ether liquid crystals are successfully applied to the imitation of biomembrane transport. Binary component membrane composed of crown ether liquid crystal and PVC was first developed. Such a novel model of biomimetic membrane is capable of imitating ingeniously the thermocontrolling transport of biomembrane, thus the essential function of liquid crystal in membane transport is more fully exploited. It was suggested, consequently, that the molecules of the crown ether liquid crystal could assemble themselves to form ionic channels, as they exist in mesophase.Of still more significance is that the thermocontrolling transport of ions through the membrane is found to be operative selectively and the permeation of ion is under the direct influence of the thermal turmoil of the crown ether liquid cr 相似文献
107.
制备了一系列V,Ag,Ni原子比不同的三元氧化物,应用TPD-MS技术研究了样品表面氧的性质,并测定了甲苯选择性氧化生成苯甲醛的催化活性。实验结果表明,样品表面存在有多种吸附的氧物种。在脱附温度<900℃:当Ni含量对Ag(或V)的原子比为0.25或0.50时,仅在低温处出现有表面的O^-和O^2^-两种氧物种的脱附峰;当Ni含量对Ag(或V)的原子比增高到>0.75时,除有表面的O^-和O^2^ 相似文献
108.
纳米TiO2膜用于光催化氧化测定化学需氧量的研究 总被引:4,自引:0,他引:4
A photocatalytic oxidation method for determination of chemical oxygen demand (COD) using nano-TiO2 film, based on the use of a nano-TiO2-Ce(SO4)2 system and electrochemical detection, was proposed. The technique was originated from the direct determination of the Ce(Ⅲ) concentration change resulting from photocatalytic oxidation of organic compounds. Ce(Ⅲ), which was produced by photocatalytic reduction of Ce(SO4)2, could be measured at a multi-walled carbon nanotubes (MWNT) chemically modified electrode (CME). The COD values by this method were calculated from the differential pulse voltammetry (DPV) current of Ce(Ⅲ) at the CME. Under the optimal operation conditions, the detection limit of 0.5 mg·L^-1 COD with the linear range of 1-600 mg·L^-1 was achieved. This method was also applied to determination of various COD of ground water and wastewater samples. The resuits were in good agreement with those from the conventional COD methods, i.e., permanganate and dichromate ones. 相似文献
109.
MinHAO DaXING QunCHEN JuanWANG 《中国化学快报》2004,15(6):679-682
This paper, for the first time, reports a method that can be used as a highly sensitive probe for singlet oxygen (^1O2) and superoxide anion (O2^-) in vitro or in vivo. FCLA(3,7-dihydro-6-{4-[2-(N‘-(5-fluoresceinyl)thioureido)ethoxy]phenyl}-2-methylimidazo{1,2-a}pyrazin-3-one sodium salt), a chemiluminescence (CL) analysis reagent, has been reported to sensitively react with ^1O2 and O2^- to emit photons with a spectral peak of 525nm. In this work,when human serum albumin (HSA) was added into FCLA solution to enhance the CL intensity,approximately 20 times, compared to that without HSA. The enhanced CL had the same 525 nm spectral peak, identical to that without HSA. By gradually reducing the molecular oxygen content in the solution, we find that the auto-oxidation of oxygen molecules dissolved in the solution plays an important role in the CL process. Based on these experimental evidences, we propose a novel and highly sensitive detection method of ^1O2 and O2^- which may have a great potential in chemical and medical applications. 相似文献
110.
On the Chemical Transport of Cr2O3 with CrI3/I2 – Experiments and Model-Calculations for Participation of CrOI2,g Gaseous chromium oxyiodides that were unknown up to now cause the migration of Cr2O3 in the temperature gradient 1 000°C→900°C when iodine (e. g. 0.1 mmol/ml) and CrI3 is added (eq. (1)). Transport agent for Cr2O3 is gaseous CrI4. With a smaller concentration of iodine (D(I2) ? 0.016 mmol/ml) and lower temperatures (e.g. T? = 850°C) the influence of H2O (from the wall of the silica ampoule) becomes more important. Under these conditions the transport of Cr2O3 is a result from the endothermic reactions (2), (3) and (4). H2,g has on the basis of the decomposition of HIg a positive difference of the solubility and H2,g should not to be considered as a transport agent. Because of the range of equilibrium-values the reaction 4 has to be taken into consideration. Estimated value of the enthalpie for CrOI2,g is fixed more precisely by thermodynamic model calculation to ΔfH°298(CrOI2,g) = ?51.4 kcal/mol. The estimated limit of error for the enthalpie of formation is smaller than ± 5 kcal/mol. Without an addition of CrI3 is in the system Cr2O3/I2 a migration of Cr2O3 not observable. 相似文献