一种估算多壁碳纳米管电化学容量的方法

Five kinds of multi-walled carbon nanotubes were prepared by CVD(Chemical Vapour Deposition) and purified under the same conditions, then were used as electrodes for super capacitors in order to compare their performance. The differences measured in terms of specific capacitance by galvanostatic cycling were presented, porosity measurements using nitrogen at 77 K made on carbon nanotubes allowd a better understanding of the electrochemical behavior of these carbon nanotubes. The experiment results show that pore diameter in the range of more than 3nm is required to maximize the capacitance in the electrolyte of 1.0 mol·L^-1 LiClO₄/EC+DEC(V_EC∶V_DEC=1∶1), and the BET surface area contributed by this extent is almost linear with the specific capacitance, in which an average value is about 0.11 F·m^-2, and the specific capacitance estimated from above is very close to the value by experiment.     

纳米氧化锰电极材料的制备和电容特性研究

The nano-MnO₂ as active electrode material for supercapacitor was synthesized by solid-state reaction between KMnO₄ and manganese acetate at room temperature. The products annealed at 100 ℃ and 200 ℃ were characterized by XRD and TEM. The results showed the sample annealed at 100 ℃ was poorly crystallized phase with an average grain size of <20 nm. Electrochemical performances of manganese oxide electrode were investigated by cyclic voltammetry and constant current charge/discharge. The manganese oxide electrode annealed at 100 ℃ in 1 mol·L^-1 Na₂SO₄ aqueous electrolyte exhibited excellent capacitive behavior between -0.2 and +0.8 V (vs SCE). By 5 mA and 10 mA constant current charge/discharge, the nano-MnO₂ annealed at 100 ℃ can provide a specific capacitance of 158.5 F·g^-1 and 151.2 F·g^-1, respectively.     

氢气泡模板电沉积多孔金属镍薄膜

Porous nickel films have been successfully electrodeposited using cathodic hydrogen bubbles as a template. The influence of deposition parameters including concentration, temperature and current density on the films morphologies has been systematically studied. SEM results showed that increase in current density resulted in the deposits with higher pore density and smaller pore size. Both the pore size and thickness of the pore walls increased with the electrolyte temperature range from 20 to 60 ℃ when the other deposition parameters were fixed. Increasing the concentration of NiCl₂ or NH₄Cl in the electrolyte led to the thicker of the pore walls and declined pore size and density. The deposits displayed a dendritic morphology in cross-sectional SEM image. Electrochemical characterization of the porous nickel films after surface oxidation in 1.0 mol·L^-1 NaOH solution showed that specific capacitance as high as 7.2 F·g^-1 could be reached.     

PMMA/定向碳纳米管复合材料导电与导热性能的研究

Methyl Methacrylate(MMA) has been filled in the apertures of aligned carbon nanotubes(ACNTs). Then PMMA/ACNTs composites have been synthesized by in-situ polymerization. The SEM results show that carbon nanotubes are well dispersed and directionally arranged in the composites. The electrical conductivities of the parallel direction (parallel with ACNTs) and perpendicular direction (perpendicular with ACNTs) of composites were respectively tested to be 15 S·cm^-1 and 4 S·cm^-1, so the composites were conductivity anisotropic. Compared with PMMA, the thermal stable temperature of composites in air was improved by 100 ℃,and the thermal conductivity of composites was 13.64 times of PMMA.     

壳聚糖/Pb(Ⅱ)模板壳聚糖膜与Pb(Ⅱ)螯合反应的动力学及机理探讨

Chitosan and chitosan membranes with Pb(Ⅱ) ion as template were studied. The adsorption isotherms were correlated by dc/dt=-kcⁿ at the temperature of 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃. By means of linear correlation, the shapes of the isotherm curves were similar to the kinetic function of 2/c^1/2=-kt and the apparent activation energy for with chitosan(123.8 kJ·moL^-1) was larger than that of membrane with Pb(Ⅱ) ion(92.3kJ·moL^-1). The chitosan membrane with Pb(Ⅱ) ion template was better “memory” function. The adsorption mechanism of chitosan with Pb(Ⅱ) was studied by IR and XPS. The results indicated that the nitrogen in -NH₂ and the oxygen in C₃-OH of chitosan were coordination atoms.     

稀土与β-二酮及2-（2-吡啶）苯并咪唑三元配合物的研究

As useful fluorescent reagent, rare earth complexes with β-diketones have been　extensively studied. Four new rare earth (La, Eu) ternary complexes with　β-diketones, (benzoylacetone (Hbza), 2-thenoyltrifluoroacetone, (HTTA)) and organic base (2-(2-pyridyl) benzimidazole, (Hpbi)) have been synthesized and characterized by elemental analysis, IR, NMR. The general formulae of these complexes are ［Ln(bza)₃(Hpbi)］ and［Ln(TTA)₃(Hpbi)］. The effects of coordinated base on UV, especially on fluorescent properties of the complexes were discussed. The results showed that the dehydro-Hpbi, pbi^{－, strongly enhances the fluorescence of the complexes.}     

LiNi0.8Co0.2O2 / MWNTs复合物超级电容器电极材料的研究

Multiwalled carbon nanotubes (MWNTs) were used as the conductive additive in the electrode materials. The electrochemical properties of supercapacitors based on LiNi_0.8Co_0.2O₂ / MWNTs composite and LiNi_0.8Co_0.2O₂/acetylene black composite and MWNTs in 1.0 mol·L^-1 LiClO₄ / EC+DEC [V(EC)∶V(DEC)=1∶1] electrolyte were investigated by means of constant charge/discharge current tests, respectively. The experimental results show that the LiNi_0.8Co_0.2O₂ / MWNTs composite has better performance than that of others, and the maximum specific capacitance of the supercapacitor can reach 271.6 F·g^-1, while the energy density is up to 339.5 Wh·kg^-1. Furthermore, it is remarkable that the performance of MWNTs is better than that of acetylene black as the conductive additive.     

Fiberoptic biosensors based on chemiluminescent reactions

The chemiluminescence of luminol in the presence of H₂O₂ has been exploited to develop fiberoptic biosensors associated with flow injection analysis systems. A chlorophenol sensor was developed based on the ability of certain halophenols to enhance the peroxidase-catalyzed luminol chemiluminescence. Horseradish peroxidase immobilized on a collagen membrane was used. Ten chlorophenols have been tested with this chemiluminescent-based sensor. The lower detection limit was obtained with 4-chloro-3-methylphenol and was equal to 0.01 μM. Electrochemiluminescent-based fiberoptic biosensors for glucose and lactate were also developed using glucose oxidase or lactate oxidase immobilized on polyamide membranes. In the presence of oxidase-generated H₂O₂, the light emission was triggered electrochemically by means of a glassy carbon electrode polarized at +425 mV vs a platinum pseudo-reference electrode. The detection limits for glucose and lactate were 150 and 60 pmol, respectively, and the dynamic ranges were linear from 150 pmol to 600 nmol and from 60 pmol to 60 nmol, respectively.     

离子层气相反应法(ILGAR)制备CuInS2薄膜的研究

CuInS₂ thin films have been prepared by ion layer gas reaction (ILGAR) using C₂H₅OH as solvent, CuCl and InCl₃ as reagents and H₂S gas as sulfuration source. The effects of cationic concentrations and numbers of cycle on the properties of CuInS₂ film were investigated. The chemical composition, crystalline structure, surface topography, deposited rate, optical and electronic properties of the films were characterized by X-ray diffractrometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), ultraviolet-visible spectrometry (UV-Vis) and Hall System. The results show that the crystalline of CuInS₂ thin films and the deposition rate have been improved with the increase of cationic concentration, while CuxS segregation phases appear with further increasing cationic concentration. The deposition rate is close to constant as cationic concentration is fixed. CuInS₂ thin film derived form lower cationic concentration is uniform, compact and good in adhesion to the substrates. The absorption coefficient of CuInS₂ thin films is larger than 10⁴ cm^-1, and the band gap E_g is in the range of 1.30～1.40 eV. The dark resisitivity of the thin film decreases from 50 to 10 Ω·cm and the carrier concentration ranges are over 10¹⁶ cm^-3.     

预氧化对石油焦物理活化的作用

Activated carbon was prepared from pretreated petroleum coke by the vapor activation. The effect of pretreatment process on activation performance of coke was studied by low temperature N₂ adsorbtion-desorption and XRD. The results show that when the temperature is increased, coke loses volatiles with obvious volume contraction, resulting in decline in coke activation performance, the activated carbon obtained from carbonization coke after treatment at 650 ℃ is with a higher degree of graphitization, while pores below 1.5nm are disappeared. The oxidation pretreatment would modify the micro-structure of the coke and make the graphitization degree of coke decline. The activation performance of coke is improved greatly by air-oxidation pretreatment due to the formation of a mass of pore in coke with specific surface area about 146 m²·g^-1, and the surface area of activated carbon is considerably increased. The specific surface area of the activated carbon from air-oxidated coke reached 499m²·g^-1. Nitric acid pretreatment also had effect on improving activating performance of the petroleum coke.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.