共查询到20条相似文献,搜索用时 15 毫秒
1.
Rika M. Y. A. Rahman M. M. Salleh A. A. Umar A. Ahmad 《Journal of Solid State Electrochemistry》2010,14(11):2089-2093
A nanoparticle TiO2 solid-state photoelectrochemical cell has been fabricated. The effect of ionic conductivity of a solid electrolyte of polyacrylonitrile
(PAN)–propylene carbonate (PC)–lithium perchlorate (LiClO4) on the performance of a photoelectrochemical cell of indium tin oxide (ITO)/TiO2/PAN–PC–LiClO4/graphite has been investigated. A nanoparticle TiO2 film was deposited onto ITO-covered glass substrate by controlled hydrolysis technique. A solid electrolyte of PAN–LiClO4 with PC plasticizer prepared by solution casting technique was used as a redox couple medium. The room temperature conductivity
of the electrolyte was determined by AC impedance spectroscopy technique. A graphite electrode was prepared onto a glass slide
by electron beam evaporation technique. The device shows a photovoltaic effect under illumination. The short-circuit current
density, J
sc, and open-circuit voltage, V
oc, vary with the conductivity of the electrolyte. The highest J
sc of 2.82 μA cm−2 and V
oc of 0.56 V were obtained at the conductivity of 4.2 × 10−4 Scm−1 and at the intensity of 100 mW cm−2. 相似文献
2.
V. N. Fokin E. E. Fokina B. P. Tarasov 《Russian Journal of Inorganic Chemistry》2018,63(12):1605-1609
A possibility for hydrogenation of a two-phase magnesium alloy containing intermetallic compound Mg2Yb by hydrogen and ammonia is found to yield hydride phases MgH2 and MgYbH3.5 in various temperature schedules. The use of ammonia in the range 350–500°C leads to the formation of magnesium and ytterbium nitrides. 相似文献
3.
Alfred Y. C. Tong Rhiannon Braund David S. Warren Barrie M. Peake 《Central European Journal of Chemistry》2012,10(4):989-1027
Pharmaceutical compounds have been detected in the environment and potentially arise from the discharge of excreted and improperly disposed medication from sewage treatment facilities. In order to minimize environmental exposure of pharmaceutical residues, a potential technique to remove pharmaceuticals from water is the use of an advanced oxidation process (AOP) involving titanium dioxide (TiO2) photocatalysis. To evaluate the extent UV/TiO2 processes have been studied for pharmaceutical degradation, a literature search using the keywords ‘titanium dioxide’, ‘photocatalysis’, ‘advanced oxidation processes’, ‘pharmaceuticals’ and ‘degradation’ were used in the ISI Web of Knowledge TM, Scopus TM and ScienceDirect TM databases up to and including articles published on 23 November 2011. The degradation rates of pharmaceuticals under UV/TiO2 treatment were dependent on type and amount of TiO2 loading, pharmaceutical concentration, the presence of electron acceptors and pH. Complete mineralization under particular experimental conditions were reported for some pharmaceuticals; however, some experiments reported evolution of toxic intermediates during the photocatalytic process. It is concluded that the UV/TiO2 system is potentially a feasible wastewater treatment process, but careful consideration of the treatment time, the loading and the type of TiO2 (doped vs. undoped) used for a particular pharmaceutical is necessary for a successful application (198 words). 相似文献
4.
de Visser SP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(15):4533-4541
Density functional calculations on a mu-oxo-mu-peroxodiiron complex (1) with a tetrapodal ligand BPP (BPP=N,N-bis(2-pyridylmethyl)-3-aminopropionate) are presented that is a biomimetic of the active site region of ribonucleotide reductase (RNR). We have studied all low-lying electronic states and show that it has close-lying broken-shell singlet and undecaplet (S=0, 5) ground states with essentially two sextet spin iron atoms. In strongly distorted electronic systems in which the two iron atoms have different spin states, the peroxo group moves considerably out of the plane of the mu-oxodiiron group due to orbital rearrangements. The calculated absorption spectra of (1,11)1 are in good agreement with experimental studies on biomimetics and RNR enzyme systems. Moreover, vibrational shifts in the spectrum due to (18)O(2) substitution of the oxygen atoms in the peroxo group follow similar trends as experimental observations. To identify whether the mu-oxo-mu-1,2-peroxodiiron or the mu-oxo-mu-1,1-peroxodiiron complexes are able to epoxidize substrates, we studied the reactivity patterns versus propene. Generally, the reactions are stepwise via radical intermediates and proceed by two-state reactivity patterns on competing singlet and undecaplet spin state surfaces. However, both the mu-oxo-mu-1,2-peroxodiiron and mu-oxo-mu-1,1-peroxodiiron complex are sluggish oxidants with high epoxidation barriers. The epoxidation barriers for the mu-oxo-mu-1,1-peroxodiiron complex are significantly lower than the ones for the mu-oxo-mu-1,2-peroxodiiron complex but still are too high to be considered for catalytic properties. Thus, theory has ruled out two possible peroxodiiron catalysts as oxidants in RNR enzymes and biomimetics and the quest to find the actual oxidant in the enzyme mechanism continues. 相似文献
5.
6.
V. N. Odinokov R. V. Shafikov R. G. Savchenko S. R. Afon’kina I. V. Galyautdinov L. M. Khalilov A. S. Shashkov 《Russian Journal of Organic Chemistry》2008,44(5):671-674
By hydrogenation of (20R,22R)-6α,14α,25-trihydroxy-and (20R,22R)-6β,14α,25-trihydroxy-2,3:20,22-bis(isopropylidenedioxy)-5α-cholest-7-enes on a catalyst (Raney nickel) the corresponding (5α,6α)-and (5β,6β)-epimers of previously unknown Δ8,14-6-hydroxy derivatives of ecdysteroids were synthesized. 相似文献
7.
The rate constant of the reaction of chlorine atoms with CH3Br was measured in a temperature range of 298–358 K using the resonance fluorescence of chlorine atoms. The possible role of this reaction in atmospheric chemistry and fire extinguishing was discussed. It was found that this reaction is homogeneous in contrast to the previously studied reaction of chlorine atoms with CH3I, with occurs at the reactor surface. 相似文献
8.
I. R. Begishev A. K. Belikov P. V. Komrakov I. S. Nikitin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(7):1319-1325
The dependence of temperature on time is investigated using a microthermocouple at different distances from a UV light source in a mixture of chlorine and chloromethane. These relationships give an idea of the size and location of a center of photoignition. It is found that if the size of the reaction vessel in the direction of the luminous flux is much greater than the dimensions of the ignition center, the thermal expansion of a reacting gas mixture has a huge impact on such photoignition parameters as the critical concentration limits and the critical intensity of UV radiation. It is found that by increasing the length of the vessel, some chlorinated combustible mixtures lose the ability to ignite when exposed to UV light. 相似文献
9.
A sol–gel route was developed to prepare pure ultrafine LiTaO3 powders using Ta2O5, Li2CO3, citric acid (CA) as chelating agent, ethylene glycol (EG) as esterification agent and polyethylene glycol (PEG) as dispersant.
The effects of pH value and heat treatment temperature of powder precursor on the synthesis of LiTaO3 powders were investigated. The phase content and morphology of the final product were evaluated by XRD, SEM and TEM. A transparent
gel was produced when heating a mixed-solution of CA, EG, Li and Ta ions with a molar ratio of [CA]:[EG]:[Li]:[Ta] = 3.0:6.0:1.0:1.0
and 2‰ PEG additions with a pH value of 7 at water bath temperature of 80 °C. The results showed that single phase LiTaO3 powders with average particle sizes of nanometers were produced after heat treatment of the powder precursor at 650, 700,
800, and 900 °C respectively for 2 h. 相似文献
10.
11.
E. M. Nikandrov D. O. Ruzanov N. S. Panina A. N. Belyaev 《Russian Journal of General Chemistry》2017,87(11):2612-2619
A new mixed-valence complex [(O)(phen)2VIV(μ-O)VV(O)phen)(mal)]+ was synthesized and characterized by the X-ray structural analysis. Its geometric structure was simulated by the DFT M06/6-31G(d,p) method. Comparison of calculated and experimental data made it possible to draw a conclusion on the oxobridging nature of the bond between vanadium fragments and to confirm the value of the target compound charge. The energy characteristics of cation formation reactions in solution were estimated. It was found that the oxidation of VIV to VV assists subsequent substitution of ligands. Joining [(O)VIV(phen)2]2+ and [(O)VV(O)(phen)(mal)]– particles proceeds by the donor-acceptor mechanism. 相似文献
12.
13.
A lanthanum metal–organic framework, [La(BTC)(H2O)(DMF)] (H3BTC = 1, 3, 5-benzenetricarboxylic acid), was synthesized under mild hydrothermal conditions. The synthesized [La(BTC)(H2O)(DMF)] was characterized by scanning electron microscopy in combination with energy dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FT-IR). Its electrochemical properties and electrocatalytic activity towards H2O2 reduction in acidic media were studied by cyclic voltammetry (CV) and amperometric current–time response. The [La(BTC)(H2O)(DMF)] modified electrode shows good electrochemical behavior and performs well electrocatalytic activity towards hydrogen peroxide (H2O2) reduction at ca. ?0.7 V. The modified electrode displays a linear range from 5 μM to 2.67 mM and a limit of detection of 0.73 μM to H2O2. The [La(BTC)(H2O)(DMF)] modified electrode also possesses good selectivity and stability. Thus, [La(BTC)(H2O)(DMF)] will be a promising material for non-enzymatic H2O2 sensor. 相似文献
14.
A. R. Makhmutov 《Kinetics and Catalysis》2017,58(6):695-700
The photocatalytic transformations of carbon tetrachloride and aliphatic primary alcohols in the presence of iron trichloride and a molar ratio of components FeCl3: CCl4: ROH = 1: 300: 2550 were studied. CCl4 is transformed into chloroform and hexachloroethane after exposure to a mercury lamp (250 W) to the FeCl3–CCl4–ROH system at 20°C, whereas the primary ROH alcohols are selectively oxidized into acetals (1,1-dialkoxyalkanes). The maximum conversion of CCl4 reaches 80%. The kinetics and mechanism of the photocatalytic conversion of the FeCl3–CCl4–ROH system are considered. 相似文献
15.
This study was prepared for the first time the trimetallic nanocatalyst Co2-Ni-Mn/SiO2 by thermal decomposition of) [Ni(H2O)5Co(dipic)2].2H2O + [Mn(H2O)5Co(dipic)2] 2H2O)/SiO2, to study the Fischer–Tropsch reaction for conversion of the synthesis gas to light olefins. The catalytic performance of Co2-Ni-Mn/SiO2 as a nanocatalyst prepared by thermal decomposition of an inorganic precursor was compared to that of the trimetallic nanocatalysts Co2-Ni-Mn/SiO2 as reference nanocatalysts prepared by impregnation and co-precipitation. The characterization of precursor and nanocatalyst were confirmed by thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) specific surface area, and X-ray diffraction (XRD). The Fischer–Tropsch reaction for all nanocatalysts of Co2-Ni-Mn/SiO2 was studied at 280–360 °C at a gas hourly space velocity of 3600 h?1, and a H2/CO molar ratio of 1:1 at atmospheric pressure. The results showed that the Co2-Ni-Mn/SiO2 nanocatalyst prepared by thermal decomposition of an inorganic complex exhibited the higher activity than the other nanocatalysts and showed maximum selectivity to light olefins at 360 °C. 相似文献
16.
A. M. Gasanaliev A. I. Rasulov B. Yu. Gamataeva A. K. Mamedova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(2):154-161
Tree of phases and crystallization were plotted via a priori prediction, and the coordinates (composition) of a nonvariant
point of a NaCl-KCl-SrCl2-Sr(NO3)2 four-component system were determined according to calculations and experimental data. The promise of the method for determining
the coordinates of nonvariant points in multicomponent systems was confirmed experimentally. The dependence of density and
electroconductivity vs. temperature was studied. The volume dilation of a melt was calculated up to the maximum operating
temperature. 相似文献
17.
A sensitive catalytic voltammetric method for determining trace iron at a bismuth film electrode (BiFE) is described. The method is based on the cathodic reduction of the Fe(III)–triethanolamine (TEA) complex to Fe(II). It has been proved that the addition of KBrO3 causes rapid oxidation of Fe(II) and TEA, and therefore results in a large increase in the analytical signal from Fe(III) when TEA is placed in alkaline solution. When TEA was present in the solution, operating the BiFE under optimized conditions yielded a stable catalytic voltammetric response for iron, with high sensitivity (0.88 A M–1), good precision (RSD=3.9%) and a low detection limit (7.7×10–9 M), obtained without any preconcentration procedure. Possible interferences from the coexisting ions and surface-active substances were investigated. Finally, the method was applied with satisfactory results to the determination of iron in certified reference river water samples. 相似文献
18.
Protonation of a Biologically Relevant CuII μ‐Thiolate Complex: Ligand Dissociation or Formation of a Protonated CuI Disulfide Species?
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Erica C. M. Ording‐Wenker Martijn van der Plas Dr. Maxime A. Siegler Dr. Célia Fonseca Guerra Prof. Dr. Elisabeth Bouwman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):16913-16921
The proton‐induced electron‐transfer reaction of a CuII μ‐thiolate complex to a CuI‐containing species has been investigated, both experimentally and computationally. The CuII μ‐thiolate complex [CuII2( LMeS )2]2+ is isolated with the new pyridyl‐containing ligand LMeSSLMe , which can form both CuII thiolate and CuI disulfide complexes, depending on the solvent. Both the CuII and the CuI complexes show reactivity upon addition of protons. The multivalent tetranuclear complex [CuI2CuII2( LS )2(CH3CN)6]4+ crystallizes after addition of two equivalents of strong acid to a solution containing the μ‐thiolate complex [CuII2( LS )2]2+ and is further analyzed in solution. This study shows that, upon addition of protons to the CuII thiolate compound, the ligand dissociates from the copper centers, in contrast to an earlier report describing redox isomerization to a CuI disulfide species that is protonated at the pyridyl moieties. Computational studies of the protonated CuII μ‐thiolate and CuI disulfide species with LSSL show that already upon addition of two equivalents of protons, ligand dissociation forming [CuI(CH3CN)4]+ and protonated ligand is energetically favored over conversion to a protonated CuI disulfide complex. 相似文献
19.
A. V. Chistyakov P. A. Zharova A. E. Gekhman V. V. Kriventsov M. V. Tsodikov 《Kinetics and Catalysis》2016,57(6):812-820
It was found that the preliminarily reduced commercial platinum–rhenium catalyst PR-71 exhibited high activity in the conversion of ethanol into C4–C12 olefins and in the cross-condensation reactions of ethanol with glycerol, acetone, n-propanol, and isopropanol. Acetone and glycerol exhibited the highest reactivity in the cross-condensation reactions; this manifested itself in an increase in the total yield of the target fraction of C4–C12 hydrocarbons and in a more than 10-fold increase in the yield of products containing the odd numbers of carbon atoms, as compared with the conversion of individual ethanol. The structural studies performed by extended X-ray absorption fine structure (EXAFS) spectroscopy and transmission electron microscopy showed that the high selectivity of PR-71 can be caused by the formation of bimetallic Pt–Re and Pt–Al clusters in the course of the prolonged preliminary reduction of the catalyst. 相似文献
20.
Combinations of SiO2–TiO2 mixed with zeolites may open new opportunities as base supports for acid-base and oxidation reactions. These solids would endow the catalysts with specific acid sites, which may not necessarily be found in those supports with only Si-Al oxides as basic materials. Using a standard sol–gel methodology, SiO2–TiO2 mixtures are prepared and mixed with β, Y and ZSM-5 zeolites. By partially hydrolyzing the SiO2 precursor at the beginning of the sol–gel procedure it is possible to maximize the number of Si–O–Ti bridges formed. FTIR and AFM analyses show that the size of sols formed depend upon the type of zeolite. Metal loading helps surface dehydroxylation of the materials, possibly indicating a good insertion of the metal into the network. 相似文献