Experimental demonstrations of high-Q superconducting coplanar waveguide resonators

We designed and successfully fabricated an absorption-type of superconducting coplanar waveguide (CPW) resonators. The resonators are made from a Niobium film (about 160 nm thick) on a high-resistance Si substrate, and each resonator is fabricated as a meandered quarter-wavelength transmission line (one end shorts to the ground and another end is capacitively coupled to a through feedline). With a vector network analyzer we measured the transmissions of the applied microwave through the resonators at ultra-low temperature (e.g., at 20 mK), and found that their loaded quality factors are significantly high, i.e., up to 10^6. With the temperature increases slowly from the base temperature (i.e., 20 mK), we observed the resonance frequencies of the resonators are blue shifted and the quality factors are lowered slightly. In principle, this type of CPW-device can integrate a series of resonators with a common feedline, making it a promising candidate of either the data bus for coupling the distant solid-state qubits or the sensitive detector of single photons.Comment: Accepted by Chinese Science Bulleti

Facile Fabrication of Highly Hydrophobic Onion-like Candle Soot-Coated Mesh for Durable Oil/Water Separation

Although sundry superhydrophobic filtrating materials have been extensively exploited for remediating water pollution arising from frequent oil spills and oily wastewater emission, the expensive reagents, rigorous reaction conditions, and poor durability severely restrict their water purification performance in practical applications. Herein, we present a facile and cost-effective method to fabricate highly hydrophobic onion-like candle soot (CS)-coated mesh for versatile oil/water separation with excellent reusability and durability. Benefiting from a superglue acting as a binder, the sub-micron CS coating composed of interconnected and intrinsic hydrophobic carbon nanoparticles stably anchors on the surface of porous substrates, which enables the mesh to be highly hydrophobic (146.8 ± 0.5°)/superoleophilic and resist the harsh environmental conditions, including acid, alkali, and salt solutions, and even ultrasonic wear. The as-prepared mesh can efficiently separate light or heavy oil/water mixtures with high separation efficiency (>99.95%), among which all the water content in filtrates is below 75 ppm. Besides, such mesh retains excellent separation performance and high hydrophobicity even after 20 cyclic tests, demonstrating its superior reusability and durability. Overall, this work not only makes the CS-coated mesh promising for durable oil/water separation, but also develops an eco-friendly approach to construct robust superhydrophobic surfaces

Computational study on the mechanism and kinetics of NO3-initiated atmosphere oxidation of vinyl acetate

It is known the NO3 radical contributes to the oxidation of volatile organic compounds in the atmosphere in the night, leading to the formation of carbonyl compounds and organic nitrates. The mechanistic and kinetic properties of NO3-initiated oxidative degradation of vinyl acetate (VAC), a typical unsaturated ester, have been studied using density functional method. According to the computational results, two types of primary reactions were identified: NO3-addition and H-abstraction. The NO3-addition reaction especially the C-beta-addition pathway dominates the entrance channel of NO3 into VAC while the H-abstraction reaction is negligible. Further reactions of the two adducts were discussed in the presence of O-2/NOx. The rate constants were estimated by using the MultiWell software. The overall rate constant of NO3-initiated oxidation of VAC was about 7.30 x 10(-15) cm(3) molecule(-1) s(-1) at 298.15 K and atmospheric pressure, in good agreement with the experimental value of (7.30 +/- 1.8) x 10(-13) cm(3) molecule(-1) s(-1). The atmospheric lifetime of VAC reacting with NO3 radicals (5.0 x 10(8) molecule cm(-3)) is about 76.1 h under atmospheric conditions

OH-Initiated Tropospheric Photooxidation of Allyl Acetate (AAC): A Theoretical Study

The mechanisms of OH-initiated oxidation of allyl acetate (AAC) in the presence of O2/NO have been investigated by performing Density Functional Theory (DFT) calculations. Two patterns (OH-addition and H-abstraction) of the initial reaction and the subsequent reactions of the primarily produced intermediates (IM1, IM2 and IM4) have been proposed. The OH addition reactionsare more favorable than the H abstraction reactions, but H abstraction from the CH2group cannot be ignored. The major degradation products have been identified. The rate coefficients and the branching ratios of the primary reactions are obtained over the temperature of 200-500 K and the pressure range of 0.001-1000 atm. The total rate coefficient is 3.17 Ă 10-11 cm3 molecule-1 s-1 at 298 K and 1 atm. With respect to the typical concentration of OH radical (2.0 Ă 106 molecule cm-3), the atmospheric lifetime of AAC is estimated to be 4.40 hours.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Photocatalytic Treatment of Methyl Orange Dye Wastewater by Porous Floating Ceramsite Loaded with Cuprous Oxide

It is well known that water treatment of printing and dyeing wastewaters is problematic. In order to decompose dyes from dyestuff wastewater and convert them into almost harmless substances for the natural environment, an easily prepared, efficient, practical, and easy-to-regenerate composite material was produced from porous floating ceramsite loaded with cuprous oxide (PFCC). The PFCC samples were prepared and characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The material was applied for photocatalytic degradation of methyl orange (MO) in water. The results show that the maximal degradation rate of MO was 92.05% when the experimental conditions were as follows: cuprous oxide loading rate of 8%, PFCC dosage of 20 g/L, the reaction time of 2 h, pH value of 8, and solution initial concentration of 30 mg/L. The degradation processes of MO fits well with the Langmuir–Hinshelwood model in reaction kinetics, and the Freundlich model in reaction thermodynamics, respectively. The degradation mechanism of MO was considered from two perspectives—one was the synergetic effect of adsorption and photocatalytic oxidation, and the other was the strong oxidation of hydroxyl radicals produced by photocatalysts

Improved reversible dehydrogenation properties of MgH2 by the synergetic effects of graphene oxide-based porous carbon and TiCl3

In this study, we used a combination of graphene oxide-based porous carbon (GC) and titanium chloride (TiCl) to improve the reversible dehydrogenation properties of magnesium hydride (MgH). Examining the effects of GC and TiCl on the hydrogen storage properties of MgH, the study found GC was a useful additive as confinement medium for promoting the reversible dehydrogenation of MgH. And TiCl was an efficient catalytic dopant. A series of controlled experiments were carried out to optimize the sample preparation method and the addition amount of GC and TiCl. In comparison with the neat MgH system, the MgH/GC-TiCl composite prepared under optimized conditions exhibited enhanced dehydrogenation kinetics and lower dehydrogenation temperature. A combination of phase/microstructure/chemical state analyses has been conducted to gain insight into the promoting effects of GC and TiCl on the reversible dehydrogenation of MgH. Our study found that GC was a useful scaffold material for tailoring the nanophase structure of MgH. And TiCl played an efficient catalytic effect. Therefore, the remarkably improved dehydrogenation properties of MgH should be attributed to the synergetic effects of nanoconfinement and catalysis

The role of oxygen vacancies of ABO3 perovskite oxides in the oxygen reduction reaction

The oxygen reduction reaction (ORR) is one of the most important electrochemical reactions in energy conversion and storage technologies, such as fuel cells and metal–air batteries. However, the sluggish kinetics of the ORR is a key factor limiting the performance of these energy storage and conversion devices. Perovskite oxides are a promising family of electrocatalysts for the ORR because of their unique physical and chemical properties, such as variable crystal structure and non-stoichiometric chemistry. Studies have shown that the catalytic properties of perovskite oxides in the ORR are largely related to oxygen vacancies, which alter their electronic and crystal structures and surface chemistry. This review summarizes recent research advances on understanding the role of oxygen vacancies of the ABO3 perovskite oxides in catalyzing the ORR. With a brief introduction of perovskite oxides, approaches to creating oxygen vacancies in the ABO3 perovskite oxides and the role of oxygen vacancies in improving their catalytic performance for the ORR are discussed. Research perspectives in this important area are highlighted

Hollow La0.5Sr0.5MnO3 nanospheres as an electrocatalyst for the oxygen reduction reaction in alkaline media

Hollow perovskite oxide LaSrMnO nanospheres are synthesized by using carbon spheres as template in the presence of citric acid. Among the samples investigated in this work, the one obtained at a sintering temperature of 700 °C exhibits the highest catalytic activity in the oxygen reduction reaction (ORR) in an alkaline electrolyte. The electrochemical measurement data shows that the sample has a positive onset potential (0.860 V) and a high limiting current density (6.48 mA cm). Furthermore, the catalyst shows a high selectivity towards methanol and a better stability than a commercial Pt/C catalyst. The hollow LaSrMnO nanoshperes described in this manuscript hold a great promise for applications in metal-air batteries and alkaline fuel cells