Zn-Organic Batteries for the Semi-Hydrogenation of Biomass Aldehyde Derivatives and Concurrently Enhanced Power Output

Electricity generation and chemical productions are both critically important for the sustainable development of modern civilization. Here, a novel bifunctional Zn-organic battery has been established for the concurrent enhanced electricity output and semi-hydrogenations of a series of biomass aldehyderivatives, for the high value-added chemical syntheses. Among them, the typical Zn-furfural (FF) battery equipped with Cu foil-supported edge-enriched Cu nanosheets as cathodic electrocatalyst (Cu NS/Cu foil), provides a maximum current density and power density of 14.6 mA cm⁻² and 2.00 mW cm⁻², respectively, and in the meantime, produces high value product, furfural alcohol (FAL). The Cu NS/Cu foil catalyst exhibits excellent electrocatalytic performance of ≈93.5 % conversion ratio and ≈93.1 % selectivity for FF semi-hydrogenation at a low potential of -1.1 V vs. Ag/AgCl by using H₂O as H source, and shows impressive performance for various biomass aldehyderivatives semi-hydrogenation.     

DFT study of chromium tricarbonyl complexes of coronene and kekulene

A quantum chemical study of the mechanism and determination of the activation barriers of intramolecular η⁶,η⁶-inner-ring haptotropic rearrangements (IHR), consisting in moving a chromium tricarbonyl group Cr(CO)₃ from one six-membered aromatic ring to another, are carried out using the density functional theory (DFT) for the respective η⁶-complexes of coronene I and kekulene II. The stationary states on the potential energy surface, determining the mechanism of η⁶,η⁶-IHR, have a lower hapticity, which is of interest for catalysis because of the possibility of coordinating an additional substrate and reagent around the transition metal during the rearrangement. The processes of η⁶,η⁶-IHR complexes I and II occur with similar energy barriers (ΔG^≠ ≈ 20–25 kcal/mol) that are lower than the barriers (ΔG^≠ ≈ 30 kcal/mol) of similar transformations previously calculated or measured for naphthalene complexes and a number of small polyaromatic hydrocarbons.     

Thermal decomposition kinetics of bisthiourea cadmuim(II) tetrathiocyanato diammine chromate(III)

Cadmium thiourea reinickate undergoes two-stage thermal decomposition on heating. The DTG peak temperatures are 291 and 469°C and the corresponding DTA temperatures are 255 and 490°C. The kinetic parameters for the first stage decomposition are E* ≈ 120kJ mole^?1; Z ≈ 1.2 × 10⁸ cm³ mole^?1 sec^?1 and ΔS* ≈ ?95 J mole^?1 K^?1. For the second stage, E* ≈ 133 kJ mole^?1; Z ≈ 6.1 × 10⁵ cm^?1 mole^?1 sec^?1 and ΔS* ≈ ?142 J mole^?1 K^?1.     

Identification of the alkalide,Na−, in Na/NH3 matrices using MCD

Codeposition of Na and NH₃ at ≈ 35 K gives rise to an absorption band at ≈ 16950 cm⁻¹ with a positive MCD å term. This band is assigned to the ¹S → ¹P transition of Na⁻ marking the first direct evidence for the existence of an alkalide in NH₃. The absorption and MCD of the solvated electron band are also observed in the near infrared at ≈ 8000 cm⁻¹.     

Gas-phase spectra of the radiative recombination of nitrogen atoms at helium temperatures

The lowering of temperature from ≈ 300 K to ≈ 10 K caused drastic changes in the spectral composition of the recombinational afterglow of N atoms: the glow due to the B³Π_gν″ | A ³Σ⁺_uν″ transition with ν′ = 12-9 (λ ≈ 580 nm and λ ≈ 540 nm) disappeared whereas levels with ν′ = 8-5 (λ ≈ 560 nm) appeared. This effect is exlained in terms of Campbell and Thrush's recombination luminescence model (emitting B ³H_g state populated by radiationless transition from the lower A ³Σ⁺_u state of the N₂ molecule).     

The impedance of the Li+/Li electrode in SOCl2

Impedance measurements have been made on a lithium electrode in SOCl₂ containing 1.8 M LiAlCl₄. Impedance loci were recorded over a range of frequencies at a series of potentials.The results confirm the existence of a film on the Li electrode which grows continuously with time. Kinetic data for the Li⁺/Li ion exchange were estimated by arranging for measurements to be made as rapidly as possible and after a practical minimum time of electrode/electrolyte contact. The exchage current density for the lithium electrode was estimated under our best conditions to be 0.48 mA/cm² and α for the Li⁺ couple ≈ 0.59.     

Temperature dependence of vibrational energy transfer in the “low” pressure competitive two-channel 1,1-cyclopropane-d2 system

Intermolecular energy transfer has been studied in the two-channel competitive isomerization of 1,1-cyclopropane-d₂, both in the neat system and in the presence of helium bath gas at values of k/k^? centered around 0.02. The competing path ways differ in threshold energy by ≈ 0.6 kcal. The temperature range 773 K to 973 K was covered. Several methods of treating the data, whether by isotopic ratios of rate constants or by temperature dependence of fall off, are each independent of a knowledge of collision cross sections. Used in conjunction, they provide measurements of these quantities. Cyclopropane is an operationally strong collider (β_ω = 1) for itself at 773 K with an average down step size, <ΔE/s> >/ 10 kcal mole ^?1 (>/ 3500 cm^?1). At 973 K the substrate is no longer a strong collider; β_ω declines to ≈ 0.55 with <ΔE/s> ≈ 5.2 kcal mole^?1. For helium the corresponding quantities are β_ω ≈ 0.078 <ΔE/s> ≈ 1.1 kcal mole ^?1 declining to β_ω ≈ 0.010 and <ΔE/s> ≈ 0.53 kcal mole^?1. The several methods of measuring these quantities give excellent independent agreement. Comparison with the earlier theoretical formulation of Tardy and Rabinovitch gives good agreement, the temperature dependence of β_ω for the weak collider, helium, follows the relation β_ω ∝ T^?m, where m /s> 2.     

IR laser induced UV fluorescence in nitric oxide

We observe UV fluorescence from a gas cell containing NO and Ar, when irradiated by a CO laser line, coincident with an NO fundamental. The power density generated cw by the CO laser does not exceed 1 $\text{kW}\text{cm}{}^2$ in the focal area. It is suggested that V-V pumping is responsible for exciting the NO X ²Π up to υ ≈ 30 from where collisional transfer into A ²Σ and B ²Π is possible.     

Adiabatic polarization energy in a simple dense fluid

In this note we prey300505 sent the results of a calculation of the adiabatic electrostatic polarization energy, P⁺, of Xe⁺ in fluid Ar over the density range 0.1–1.4 g cm^?3. P₊ was expressed in terms of Lekner's screening function which, within the framework of the Kirkwood approximation, is determined by the (neutral) solute-solvent and the solvent-solvent pair correlation functions. The density dependence of P₊ can be quite well approximated (within ≈10%) by the Born charging energy with the effective ionic radius being identified with the effective hard-core diameter for the (neutral) solute-solvent separation. The P₊ data, together with experimental spectroscope results for the density dependence of the ionization potential of Xe and of CH₃I, result in preliminary information concerning the ground state energy of the quasi-free electron in fluid Ar over a wide density range.     

Vibrational energy transfer in the two-channel 1,1-cyclopropane-d2 isomerization system. Krypton bath gas

The study of intermolecular energy transfer in the 1,1-cyclopropane-d₂ system has been repeated for the neat gas at 973 K and has been extended to krypton bath gas at 823 K and 973 K. The method of study is by the competitive collisional activation “spectroscopy” technique for this two-channel competitive isomerization system. Results at 823 K give the relative collisional efficiency of krypton as β ≈ 0.46, at k/k_∞ ≈ 0.02 and yield the average down-jump energy step as 〈ΔE〉 ≈ 1200 cm^?1 on the basis of a stepladder model for the distribution of down-step sizes. At 973 K and k/k_∞ = 0.02, β ≈ 0.07 and 〈ΔE〉 ≈ 500 cm^?8, for both an exponential and stepladder distribution of down-step sizes. Agreement with related earlier data for other bath gases and for neat cyclopropane is good and verifies again a decrease in energy transfer collisional efficiency, and a decrease in 〈ΔE〉, with rise of temperature, as previously reported for this system.     

Rechargeable Aluminium–Sulfur Battery with Improved Electrochemical Performance by Cobalt-Containing Electrocatalyst

The rechargeable aluminium–sulfur (Al–S) battery is regarded as a potential alternative beyond lithium-ion battery system owing to its safety, promising energy density, and the high earth abundance of the constituent electrode materials, however, sluggish kinetic response and short life-span are the major issues that limit the battery development towards applications. In this article, we report Co^II,III as an electrochemical catalyst in the sulfur cathode that renders a reduced discharge–charge voltage hysteresis and improved capacity retention and rate capability for Al–S batteries. The structural and electrochemical analysis suggest that the catalytic effect of Co^II,III is closely associated with the formation of cobalt sulfides and the changes in the valence states of the Co^II,III during the electrochemical reactions of the sulfur species, which lead to improved reaction kinetics and sulfur utilization in the cathode. The Al–S battery, assembled with the cathode consisting of Co^II,III decorated carbon matrix, demonstrates a considerably reduced voltage hysteresis of 0.8 V, a reversible specific capacity of ≈500 mAh g⁻¹ at 1 A g⁻¹ after 200 discharge–charge cycles and of ≈300 mAh g⁻¹ at 3 A g⁻¹.     

Triplet EPR of fluorobenzonitriles

The triplet EPR spectra of the three monofluorobenzonitriles in ethanol glasses at ≈90 K have been compared. Ortho- and meta-fluorine merely broaden the ΔM = 2 signals, whereas para-fluorine produces a 54 G splitting. In accord with simple symmetry considerations, the ³La state of benzonitrile is predominately a 1,4-diradical with little free spin density at the ortho and meta positions.     

Solution-Processed White Circularly Polarized Organic Light-Emitting Diodes Based on Chiral Binaphthyl Emitters

By combining the blue and orange CPL or functionalized bis-benzoxanethones emitters (S-/R- BN-tCz and S-/R- BN-PXZ ), warm white CP-OLEDs were fabricated using solution-processed single emitting layer strategy. The successful realization of white CP-EL benefited from the same stable binaphthyl chirality and similar rigid structure of the two emissive CPL emitters. The devices exhibited the low turn-on voltage of ≈4.3 V, maximum luminance of ≈10200 cd m⁻² and maximum current efficiency of ≈2.0 cd A⁻¹. Most significantly, the devices with CIE coordinates of (0.32, 0.45) displayed intense CP-EL signals in the spectral range of 450 to 650 nm, and showed stable g_EL values of ≈10⁻³ as the luminance increased from 100 to 6000 cd m⁻². To the best of our knowledge, this work provides for the first time a simple and feasible strategy to fabricate solution-processed white CP-OLEDs based on the co-doping of the CPL emitters.     

On xenon molecule excited state lifetimes

Time-resolved excitation spectra of xenon vapor in the 150 nm region are analysed in terms of four main fluorescence lifetimes corresponding to decays of four stable excited electronic states of the Xe dimer. The two shortest decay times, ≈ 2 ns and ≈ 60 ns, are assigned to the direct radiative relaxation of the two lowest excited ungerade states, (¹Σ⁺_u)0⁺_u and (³Σ⁺_u))1 u respectively. The two longest decay times, ≈ 150 ns and ≈ 500 ns, must correspond to the overall depopulation rates of the two lowest excited gerade states, (³Σ⁺_g)1g and (¹Σ⁺_g)0⁺_g, decaying into the gerade ground state by cascading down through the intermediate ungerade states.     

Ultraviolet emission of molecular chlorine

The UV emission of Cl₂ from a new valence-shell state having 0⁺_u symmetry (T_c ≈ 59774 cm^?1, r_c ≈ 3.0 Å) was observed by focusing ≈ 500 nm laser radiation to gaseous chlorine. Excitation was achieved by virtual two-photon absorption from the B ³Π_0⁺u state formed by single-photon absorption stepwisely. The emission spectra showed transitions to the ground state as well as to the repulsive grade estate dissociating to Cl²P) + Cl(²P) products.     

RUPTURING OF POLYMER FILMS WITH RUBBING-INDUCED SURFACE DEFECTS

It has been a long-standing question whether dewetting of polymer film from non-wettable substrate surfaceswherein the bicontinuous morphology never forms in the dewetting film is due to spinodal instability or heterogeneousnucleation. In this experiment, we use a simple method to make the distinction through introduction of topographical defectsof the films by rubbing the sample surface with a rayon cloth. Spinodal dewetting is identified for those films that dewet by acharateristic wavevector, q, independent of the density of rubbing-induced defects. Heterogeneous nucleation, on the otherhand, is identified for those with q increasing with increasing density of defects. Our result shows that PS films on oxidecoated silicon with thickness less than ≈ 13 nm are dominated by spinodal dewetting, but the thicker films are dominated bynucleation dewetting. We also confirm that spinodal dewetting does not necessarily lead to a bicontinuous morphology in thedewetting film, contrary to the classic theory of Cahn.     

Ultrathin,Porous and Oxygen Vacancies‐Enriched Ag/WO3−x Heterostructures for Electrocatalytic Hydrogen Evolution

Exploring advanced electrocatalysts for electrocatalytic hydrogen evolution is highly desired but remains a challenge due to the lack of an efficient preparation method and reasonable structural design. Herein, we deliberately designed novel Ag/WO_3?x heterostructures through a supercritical CO₂‐assisted exfoliation‐oxidation route and the subsequent loading of Ag nanoparticles. The ultrathin and oxygen vacancies‐enriched WO_3?x nanosheets are ideal substrates for loading Ag nanoparticles, which can largely increase the active site density and improve electron transport. Besides, the resultant WO_3?x nanosheets with porous structure can form during the electrochemical cycling process induced by an electric field. As a result, the exquisite Ag/WO_3?x heterostructures show an enhanced hydrogen evolution reaction (HER) activity with a low onset overpotential of ≈30 mV, a small Tafel slope of ≈40 mV dec^?1 at 10 mA cm^?2, and as well as long‐term durability. This work sheds light on material design and preparation, and even opens up an avenue for the development of high‐efficiency electrocatalysts.     

Arborescent polystyrene‐graft‐poly(tert‐butyl methacrylate) copolymers: Synthesis and enhanced polyelectrolyte effect in solution

A technique is described for the preparation of arborescent graft copolymers containing poly(tert‐butyl methacrylate) (PtBMA) segments. For this purpose, tert‐butyl methacrylate is first polymerized with 1,1‐diphenyl‐2‐methylpentyllithium in tetrahydrofuran. The graft copolymers are obtained by addition of a solution of a bromomethylated polystyrene substrate to the living PtBMA macroanion solution. Copolymers incorporating either short (M_w ≈ 5000) or long (M_w ≈ 30,000) PtBMA side chains were prepared by grafting onto linear, comb‐branched (G0), G1, and G2 bromomethylated arborescent polystyrenes. Branching functionalities ranging from 9 to 4500 and molecular weights ranging from 8.8 × 10⁴ to 6.3 × 10⁷ were obtained for the copolymers, while maintaining a low apparent polydispersity index (M_w/M_n ≈ 1.14–1.25). Arborescent polystyrene‐graft‐poly(methacrylic acid) (PMAA) copolymers were obtained by hydrolysis of the tert‐butyl methacrylate units. Dynamic light scattering measurements showed that the arborescent PMAA copolymers are more expanded than their linear PMAA analogues when neutralized with NaOH. This effect is attributed to the higher charge density in the branched arborescent copolymer structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2335–2346, 2008     

One-electron oxidation and demetalation of metalloporphyrins and chlorophyll a in dichloroethane solutions as studied by pulse radiolysis

Formation of cation radicals by pulse radiolysis of metalloporphyrins and chlorophyll a in 1,2-dichloroethane is reported Demetalation of the metalloporphyrin by radiolytically produced HC1 is also observed. Rate constants for demetalation of ZnTPP and Chl a are 1 1 × 10⁸ and ≈ 3 × 10⁸ M^?1 S^?1. Oxidation of Chl a by ZnTPP⁺ has a rate constant of ≈ 4× 10⁹ M^?1S^?1.     

A time-resolved EPR study of the magnetic and decay properties of short-lived non-phosphorescent 3nπ* pyridazine

The properties of ³nπ^* pyridazine were investigated by time-resolved EPR. The zfs (X = 0.092 cm⁻¹, Y = −0.162 cm⁻¹, Z = 0.071 cm⁻¹), the sublevel decay rate constants (k_x ≈ k_z ≈ 2.0×10⁵ s⁻¹, k_y = 1.7×10⁶ s⁻¹) and the relative populating rates (P_x: P_y: P_z ≈ 0.1 : 1 : 0.1) were determined. The lack of phosphorescence is ascribed to a very large radiationless decay rate constant (k^nr ≈ 10⁶ s⁻¹).