Optical and Electrical Properties of Polymerizing Plasmas and Their Correlation with DLC Film Properties

Diamond-like carbon (DLC) films were grown from radiofrequency plasmas of acetylene-argon mixtures, at different excitation powers, P. The effects of this parameter on the plasma potential, electron density, electron temperature, and plasma activity were investigated using a Langmuir probe. The mean electron temperature increased from about 0.5 to about 7.0 eV while the mean electron density decreased from about 1.2 × 10⁹ to about 0.2 × 10⁹ cm^–3 as P was increased from 25 to 150 W. Both the plasma potential and the plasma activity were found to increase with increasing P. Through actinometric optical emission spectrometry, the relative concentrations of CH, [CH], and H, [H], in the discharge were mapped as a function of the applied power. A rise in [H] and a fall in [CH] with increasing P were observed and are discussed in relation to the plasma characteristics and the subimplantation model. The optical properties of the films were calculated from ultraviolet-visible spectroscopic data; the surface resistivity was measured by the two-point probe method. The optical gap, E _G, and the surface resistivity, _s, fall with increasing P. E _G and _s are in the ranges of about 2.0–1.3 eV and 10¹⁴–10¹⁶ /, respectively. The plasma power also influences the film self-bias, V _b, via a linear dependence, and the effect of V _b on ion bombardment during growth is addressed together with variation in the relative densities of sp² and sp³ bonds in the films as determined by Raman spectroscopy.     

Oxidation of Methanol on Pt,Pt–Ru,and Pt–Ru–Mo Electrocatalysts Dispersed in Polyaniline: An in situ Infrared Reflectance Spectroscopy Study

The electrochemical oxidation of methanol was investigated on a Pt–Ru–Mo catalyst with an in situ infrared reflectance spectroscopy. The electrocatalysts were prepared by an electrochemical deposition and dispersed in a conducting three-dimensional matrix of polyaniline (PAni). We observed that CO₂ is produced from methanol oxidation at 350 mV vs. RHE on PAni/Pt–Ru–Mo, which is 100 mV less negative than on PAni/Pt–Ru and 200 mV less than on PAni/Pt. The results suggest that Pt–Ru–Mo is less sensitive to CO_ADS poisoning than Pt–Ru and much more sensitive than Pt. Large differences are observed concerning the average wavenumber of _ADS between Pt–Ru–Mo, Pt–Ru, and Pt.     

Electrical Double Layer Structure on Electrodes of Platinum Metals: Effect of the Carbon Monoxide Adsorption

Results on the paper's theme are reviewed. Attention is focused mainly on the use of transients of current and open-circuit potential for elucidating changes in the structure of the electrical double layer (EDL) caused by the CO adsorption. It is shown that the high binding energy of CO with surfaces of platinum metals leads to a strong suppression of the total differential capacitance of the electrode, the recharge of the surface, the displacement of strongly adsorbed atoms formed during the adsorption of ions with a total charge transfer, and to other alterations in the EDL plates facing both solution and metal. The importance of allowing for double-layer effects when solving problems of electrocatalysis on platinum metals is emphasized.     

多壁碳纳米管储氢的物理吸附特性

The physisorption of hydrogen stored in armchair multi-walled carbon nanotubes (MWCNTs) is simulated by the grand canonical Monte Carlo (GCMC) method on the condition of 10 MPa at normalt emperature. Hydrogen-hydrogen and hydrogen-carbon interactions are both modeled with Lennard-Jones potential. The hydrogen storage in double-walled carbon-nanotubes (DWCNTs) has been investigated on the condition that the internal or external radius is changed while the other radius remains constant. The results show that hydrogen molecules are mostly absorbed near the tube walls, and the hydrogens to rage capacityisim proved effectively when the difference between the internal radius and the external radius increases from 0.34 to 0.61 or 0.88 nm. Its simple theoretic explanation also is given. Further more, the capacity of hydrogen physisorbed in there-walled carbon nanotubes (TWCNTs) is calculated when the wall-wall distance is 0.34, 0.61 and 0.88 nm respectively. Then its hydrogen storage capacity is compared with that of single-walled carbon nanotubes (SWCNTs) and DWCNTs, and it is discovered that the capacity of hydrogen physisorbed in MWCNTs decreases as the number of wall increases.     

双核有机金属化合物的光化学反应探析

有机金属化合物是指分子中至少含有一个金属-碳键（M-C键）的化合物,包括含M-C σ-键、M-Cnπ-键、ηn-M-Cn大π-键的化合物.双核金属-金属碳键的有机化合物的光化学反应包括光诱导金属-金属键的断裂、配体的离解与取代、光化学插入反应、光诱导异构化反应、歧化反应等.     

氟离子与磺化反应改性多壁纳米碳管催化剂的制备、表征及催化酯化反应合成油酸甲酯性能

通过高温浸渍法,对多壁纳米碳管进行了氟离子与浓硫酸磺化反应修饰改性处理,制备了一种新型Lewis酸型催化剂F^--SO₄^2-/MWCNTs,并通过透射电镜、拉曼光谱、X射线光电子能谱、吡啶吸附红外光谱、X射线荧光光谱、X射线衍射和NH₃程序升温脱附等表征手段对其的物理化学性能进行了表征分析,进而对多壁纳米碳管经F-与浓硫酸磺化反应修饰改性后所出现的结构与催化性能变化的内在影响规律进行了探索。以F^--SO₄^2-/MWCNTs为催化剂,以甲醇和油酸为原料,对其在应用于催化酯化反应合成油酸甲酯过程中的活性进行了研究。结果表明：当反应温度为65℃、醇油物质的量之比为12：1、催化剂质量占反应物总质量的0.9%、反应时间为6 h,油酸的转化率最高,达到了90%。高催化活性可归因于随着氟元素的加入,提高了SO₄^2-的插层作用效果,从而增加了酸性活性位的数量;此外,S=O键具有电子诱导效应,而F-有强负电性,两者之间发生强烈的相互作用后形成了F-S键,使S=O的吸电子效应大幅度增强,从而加剧了F^--SO₄^2-/MWCNTs催化剂的体系电荷不平衡趋势,导致催化剂中的正电荷过剩,使催化剂中的酸性活性位以Lewis酸为主,有效的避免了单纯磺化反应作用所生成的催化剂的酸性活性位以Brönsted酸型为主,而易在富含水的反应介质中发生水合作用而降低,甚至失去催化活性的现象发生。     

STUDIES OF THE MOBILITY OF SURFACE CARBON FORMED BY THE DECOMPOSITION OF METHANE ON SUPPORTED TRANSITION METAL CATALYSTS

IntroductionInformationonrelativereactiviticsofsuffocccarbonfromthcdecompositionofmethaneontransitionmetalcataIystspla}.simportantruleinourunderstandingthenatllreofeffcctiveutiliZaionofmethane.Asignificantamountofdataonthissubjecthavealread}'bccnaccumulatcd.Itx"asdiscovercdthatrcactiviticsofthesuffocecarbonstrongl}'dependonthcstructuralparameters-suchasthctyPcofsuffocecarbon.thestrengthofsurfacecarbon-metalinteractionsandthetendencyoftransformationamongthemll'2].0fspecialsarcthatthenatureofth…     

Alkylhydrazides and their protonated forms: Physical methods andab initio calculations

The basicity of hydrazides of the highest aliphatic carboxylic acids RC(O)NHNH₂ (R = C_nH_2n+1,n = 5-12) has been studied by potentiometric titration, and IR and¹H NMR spectroscopy.Ab initio Hartree-Fork calculations using the 6–31G^* basis set with full optimization of geometry were carried out on the simplest acy1hydrazines and their possible protonated forms. Based on these calculations, and the 1R and¹H NMR spectra, the tautomerism of alkylhydrazides and the structures of their protonated forms are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2645–2649, November, 1996.     

One-pot triple functionalization of carbon nanotubes

Carbon nanotubes (CNTs) are very promising as carriers for the delivery of bioactive molecules. The multifunctionalization of CNTs is necessary to impart multimodalities for the development of future CNT-based multipotent therapeutic constructs. In this context, we report the first example of covalent trifunctionalization of different types of CNTs. Our strategy is a simple and efficient methodology based on the simultaneous functionalization of the nanotube surface with three different active groups. The reaction is performed in one step by arylation with diazonium salts generated in situ. The CNTs are functionalized with benzylamine moieties blocked with three different protecting groups that can be selectively removed under specific conditions. The trifunctionalized CNTs were characterized by TEM, thermogravimetric analysis, and Raman and UV/Vis/NIR spectroscopy, while the amine loading was determined by using the Kaiser test. The sequential removal of the protecting groups of the amine functions allows the grafting of the molecules of interest on the nanotube surface to be controlled.