- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Photocatalytic Activation of C-H Bonds by Spatially Controlled Chlorine and Titanium on the Silicate Layer
摘要： Owing to the economic and environmental benefits, photocatalytic organic transformation via C-H activation is a crucially important, while still challenging area. We report photocatalytic process for partial cyclohexane oxidation with enhanced catalytic activity that exploits chlorine and titanium atoms spatially arranged on a silica substrate. Silica-based catalysts bearing grafted titanium that effectively interacts with photochemically adsorbed chlorine were prepared. The catalysts were synthesized by reacting a layered silicate with titanium(IV) acetylacetonate and subsequent chlorination treatment. Characterization by a variety of techniques revealed that the organic ligand of the titanium species that is grafted onto the silicate layer surface is converted into chlorine while maintaining its coordination state. However, upon subsequent hydration, the chlorine existed as HCl. We investigated the performance of the catalyst for the production of cyclohexanol and cyclohexanone from cyclohexane with molecular oxygen under solar light irradiation. The chlorinated layered silicate photocatalyst exhibited a remarkably high production rate (0.7 mmol g-1 h-1) and large amount of product formed (0.8 mmol), while the over-oxidation of cyclohexane was inhibited. The enhanced catalytic ability could be explained by the presence of a radical mediator (chlorine) located at a position neighboring an isolated titanium atom. The high surface density of these active species (both titanium and chlorine) on the silicate layer provided suitable electron transfer to form chlorine radicals.
关键词： Photocatalysis,partial oxidation,C-H activation,KA oil,layered silicate,titanosilicate,chlorine,cyclohexane oxidation
更新于2025-11-19 16:51:07
-
Effect of UV wavelength on humic acid degradation and disinfection by-product formation during the UV/chlorine process
摘要： The efficiency of the ultraviolet (UV)/chlorine process strongly depends on UV wavelength because chlorine photolysis and its subsequent radical formation are highly wavelength-dependent. This study compared the degradation of humic acid (HA) during the UV/chlorine process by low pressure mercury lamp (LPUV, 254 nm) and ultraviolet light-emitting diode (UV-LED, 275 and 310 nm). The results indicated that HA degradation followed the pseudo-first-order kinetics, and the fluence-based degradation rate constants (kobs) were significantly affected by UV wavelength and solution pH. HA degradation decreased greatly with increasing solution pH during the UV/chlorine process at 254 nm, while the opposite trend was observed at 275 and 310 nm. In the meantime, kobs decreased in the order of 275 nm > 254 nm > 310 nm at pH > 7.0. The changes of chlorine molar absorption coefficients at different UV wavelengths resulted in the variation of chlorine photodecay rates (kobs, chlorine), and the synergistic effects of kobs, chlorine and chlorine quantum yields (Φchlorine) affected HA reduction. The formation of disinfection by-products (DBPs) during the UV/chlorine process was also evaluated. A significant suppression on DBP formation and DBP-associated calculated theoretical cytotoxicity were observed at 275 nm high UV fluence and alkaline pHs. These findings in this study demonstrate that UV wavelength at 275 nm is more suitable for HA degradation by the UV/chlorine advanced oxidation process in practical applications.
关键词： Disinfection by-products,Ultraviolet light-emitting diode (UV-LED),UV/chlorine,Humic acid,Toxicity,UV wavelength
更新于2025-11-19 16:46:39
-
Nitrogen-embedded small-molecule semiconducting materials: Effect of chlorine atoms on their electrochemical, self-assembly, and carrier transport properties
摘要： We reported three novel nitrogen-embedded small molecules 4a, 4b, and 4c, which were synthesized from the condensation reactions of benzo[1,2-b:4,5-b']difuran-2,6(3H,7H)-dione with 1-(2-ethylhexyl)-1H-pyrrolo[2,3-b]pyridine-2,3-dione, 6-chloro-1-(2-ethylhexyl)-1H-pyrrolo[2,3-b]pyridine-2,3-dione, or 4,6-dichloro-1-(2-ethylhexyl)-1H-pyrrolo[2,3-b]pyridine-2,3-dione, respectively. Their optical, electrochemical properties, self-assembly behavior, and carrier transport properties were studied by a range of experimental and theoretical methods, and the effect of chlorine atoms were well discussed. Energy levels of the highest occupied molecular orbitals and the lowest unoccupied ones for these molecular materials locate at ?5.92～?6.02 and ?4.25～?4.37 eV, respectively. Bottom gate/bottom contact field-effect transistors based on 4a, 4b, and 4c exhibited n-channel transport characteristics with the highest electron mobility of 7.57 × 10?3 cm2 V?1 s?1. Thin film microstructure investigations revealed 4a and 4c perform lamellar molecular packing with random orientations to the OTS-treated SiO2 substrate, while 4b conducts a highly crystalline, edge-on, lamellar packing though large grain boundaries exist in its thin film.
关键词： Isoindigo derivatives,Chlorine atoms,Small-molecule semiconductors,Electron mobilities,Organic field-effect transistors
更新于2025-09-23 15:23:52
-
Degradation of Ciprofloxacin and Inactivation of Ciprofloxacin Resistant E. Faecium during UV-LED (275 nm)/Chlorine Process
摘要： Ciprofloxacin and ciprofloxacin-resistant bacteria are emerging concerns that threaten public health due to the heavy use of antibiotics and the development of bacterial resistance in water environments. In this study, we examined an energy-efficient treatment driven by a UV-LED/chlorine reaction with UV-LED chip emitting UV275 nm to remove ciprofloxacin and ciprofloxacin-resistant bacteria in water. Ciprofloxacin degradation during the UV-LED/chlorine reaction followed pseudo-first-order kinetics, and the excessive chlorine dosage has a negative effect on ciprofloxacin removal. Alkaline pH showed the best efficiency for ciprofloxacin removal, and the reactive chlorine species (RCS) played a major role at alkaline pH values. The cleavages of piperazine, cyclopropyl, and quinolone moieties are considered as the principal degradation reactions in the UV-LED/chlorine reaction. Seven byproducts (m/z = 362.9262, 306.1246, 289.0995, 288.1504, 263.0825, 147.0657, and 1183.9977), two chlorinated compounds (chloroform and chlorate) and two anions (formate and nitrate ions) were observed as the identified byproducts. Toxicity of tentatively identified byproducts were estimated by using quantitative structure activity relationship (QSAR). The complete detoxification of D. magna was achieved when applying UV-LED/chlorine process into hospital wastewater containing CIP. The UV-LED/chlorine process showed the best disinfection ability of E. faecium compared to UV-LED photolysis, chlorination, and UV-LED/H2O2 reactions. A significantly lower EE/O value (6.63 × 10-2 kWh/m3/order) during the UV-LED/chlorine reaction was also observed. Our results indicate that the UV-LED/chlorine process can effectively degrade ciprofloxacin and inactivate ciprofloxacin-resistant bacteria.
关键词： toxicity,UV-LED,ciprofloxacin,byproducts,antibiotic-resistant bacteria,Chlorine
更新于2025-09-23 15:21:01
-
Chromophores in cellulosics, XVIII. Degradation of the cellulosic key chromophore 5,8-dihydroxy-[1,4]-naphthoquinone under conditions of chlorine dioxide pulp bleaching: a combined experimental and theoretical study
摘要： DHNQ is one of the key chromophores occurring in all types of aged cellulosics. This study investigates the degradation of DHNQ by chlorine dioxide at moderately acidic (pH 3) conditions, corresponding to the conditions of industrial bleaching ("D stage"). The degradation involves three major pathways. As initial reaction, a hydrogen transfer from DHNQ to chlorine dioxide via a PCET mechanism occurs to form a radical DHNQ(cid:2) and chlorous acid. DHNQ(cid:2) is then attacked by water to give a pentahydroxynaphthalene radical PHN(cid:2) that is stabilized by strong delocalization of the non-paired electron into its aromatic ring. PHN(cid:2) immediately disproportionates to give the observable intermediate 1,2,4,5,8-pentahydroxynapththalene (I), which was comprehensively con?rmed by NMR and MS (path A). In the presence of excess ClO2, I is immediately further oxidized into acetic acid, glycolic acid, oxalic acid and CO2 as the ?nal, stable, and non-colored products (path C). In the absence of excess ClO2, elimination of water from I regenerates DHNQ (path B), so that at roughly equimolar DHNQ/ClO2 ratios ClO2 is fully consumed while a major part of DHNQ is recovered. To avoid such DHNQ "recycling" under ClO2 consumption—and to completely degrade DHNQ to colorless degradation products instead—ClO2 must be applied in at least ?vefold molar excess relative to DHNQ.
关键词： Density functional theory (DFT),Ab initio calculations,Yellowing,Cellulose,Brightness,Chromophores,5,8-dihydroxy-[1,4]-naphthoquinone,Chlorine dioxide,Brightness reversion,Pulp bleaching
更新于2025-09-23 15:21:01
-
Investigation of the Physical Properties of Plasma Enhanced Atomic Layer Deposited Silicon Nitride as Etch Stopper
摘要： Correlations between physical properties linking film quality with wet etch rate (WER), one of the leading figures of merit, in plasma-enhanced atomic layer deposition (PEALD) grown silicon nitride (SiNx) films remain largely unresearched. Achieving a low WER of a SiNx film is especially significant in its use as an etch stopper for technology beyond 7 nm node semiconductor processing. Herein, we explore the correlation between the hydrogen concentration, hydrogen bonding states, bulk film density, residual impurity concentration, and the WERs of PEALD SiNx using Fourier transform infrared spectrometry, X-ray reflectivity, and spectroscopic ellipsometry, etc. PEALD SiNx films for this study were deposited using hexachlorodisilane and hollow cathode plasma source under a range of process temperatures (270 °C – 360 °C) and plasma gas compositions (N2/NH3 or Ar/NH3) to understand the influence of hydrogen concentration, hydrogen bonding states, bulk film density, and residual impurity concentration on the WER. Varying hydrogen concentration and differences in the hydrogen bonding states resulted in different bulk film densities, and accordingly, a variation in WER. We observe a linear relationship between hydrogen bonding concentration and WER as well as a reciprocal relationship between bulk film density and WER. Analogous to the PECVD SiNx processes, a reduction in hydrogen bonding concentration arises from either (1) thermal activation or (2) plasma excited species. However, unlike the case with silane (SiH4)-based PECVD SiNx, PEALD SiNx WERs are affected by residual impurities of Si precursors (i.e., chlorine impurity). Thus, possible wet etching mechanisms in HF in which the WER is affected by hydrogen bonding states or residual impurities are proposed. The shifts of amine basicity in SiNx due to different hydrogen bonding states and the changes in Si electrophilicity due to Cl impurity content are suggested as the main mechanisms that influence WER in the PEALD processes.
关键词： plasma-enhanced ALD (PEALD),bulk film density,hexachlorodisilane (HCDS),wet etch rate (WER),silicon nitride,hydrogen/chlorine content,atomic layer deposition (ALD),hydrogen bonding state
更新于2025-09-23 15:21:01
-
Understanding the Performance of Organic Photovoltaics under Indoor and Outdoor Conditions: Effects of Chlorination of Donor Polymers
摘要： Understanding the effects of the chemical structures of donor polymers on the photovoltaic properties of their corresponding organic photovoltaic (OPV) devices under various light-intensity conditions is important for improving the performance of these devices. We synthesized a series of copolymers based on poly[(2,6-(4,8-bis(5-(2-thioethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione)] (PBDB-TS) and studied the effects of chlorine substitution of its thiophene-substituted benzodithiophene (BDT-Th) unit on its photovoltaic properties. The chlorination of the polymer resulted in a bulk heterojunction (BHJ) morphology optimized for efficient charge transport with suppressed leakage current and an increased open-circuit voltage of the OPV device; this optimization led to a remarkable enhancement of the OPV device’s power conversion efficiency (PCE) not only under the condition of 1 sun illumination but also under the condition of low light intensity mimicking indoor light; the PCE increased from 8.7% for PBDB-TS to ~13% for the chlorinated polymers, PBDT-TS-3Cl and PBDT-TS-4Cl, under the 1 sun illumination condition and from 5.3% for PBDB-TS to 21.7% for PBDB-TS-4Cl under 500 lx fluorescence illuminance. Interestingly, although the OPV PCEs under 1 sun illumination were independent of the position of chlorine substitution onto the polymer, the PBDB-TS-4Cl exhibited better performance under simulated indoor light than its derivative PBDB-TS-3Cl. Our results demonstrate that efficient light absorption and charge-carrier generation play key roles in achieving high OPV efficiency under low-light-intensity conditions.
关键词： bulk heterojunction,benzodithiophene,indoor light,chlorine substitution,organic photovoltaic
更新于2025-09-23 15:19:57
-
White luminescent single-crystalline chlorinated graphene quantum dots
摘要： White luminescent materials have been generating much excitement because of their wide-ranging potential applications. However, challenging synthesis, cytotoxicity and performance of current reported white luminescent materials still hinder their potential applications. Owing to their non-toxicity, excellent optical properties, and amenability to surface modification, white-light-emitting graphene quantum dots (WGQDs) are considered to be a next-generation white luminescent material to replace these above-mentioned conventional materials. The inherent challenge in WGQDs is their massive defects are known to give poor white optical properties. In the proof-of-concept, we designed and synthesized a novel WGQDs via a solvothermal molecular fusion route. The modulation of chlorine doping amount and reaction temperature gives the WGQDs a single-crystalline structure, bright white fluorescence and novel white phosphorescence performance for the first time. An optimum fluorescence quantum yield of WGQDs is 34%, which exceeds the majority of reported WGQDs and other white luminescent materials. The WGQDs display broad-spectrum absorption within almost the entire visible light region, broad full width at half maximum and extend their phosphorescence emission to the entire white long-wavelength region. This unique dual-mode optical characteristic of the WGQDs enlarges their applications in white light emission devices, cell nuclei imaging, and information encryption.
关键词： solvothermal molecular fusion,white luminescent materials,fluorescence,graphene quantum dots,phosphorescence,chlorine doping
更新于2025-09-23 15:19:57
-
Understanding the effects of chlorine ion on water structure from a Raman spectroscopic investigation up to 573?K
摘要： The OH stretch band features on Raman spectra of aqueous KCl?H2O solutions have been investigated at temperatures (T) up to 573 K. KCl greatly reduces the relative intensity of the shoulder at ~3245 cm–1 and the band width, but these effects are slightly reversed at temperatures over ~513 K. Also, KCl causes a blue shift (T < 433 K) but a red shift (T > 433 K) of the main peak. These spectral features are interpreted that Cl? breaks the tetrahedral hydrogen bonding (HB) structure and bonds to water molecules with the non-tetrahedral HB configurations. The single donor is likely the preferred configuration between the water molecules in the Cl? hydration shells. Cl? tends to promote the HB degree in solutions at T > 433 K.
关键词： Temperature,Chlorine ion,Hydrogen bonding,Raman spectroscopy,Water structure
更新于2025-09-19 17:15:36
-
Quick and Practical Cleaning Process for Silicon Carbide Epitaxial Reactor
摘要： In order to develop a quick and practical cleaning process for the silicon carbide chemical vapor deposition reactor, a pyrolytic carbon-coated susceptor was used. A 30-μm-thick silicon carbide film was formed on the susceptor; the film was cleaned by chlorine trifluoride gas at 460 oC for 15 min. The remained fluorine was removed by the annealing at 900 oC in ambient hydrogen. The pyrolytic carbon surface did not suffer from any damage, because the pyrolytic carbon film surface morphology after the cleaning process was the same that before the silicon carbide film deposition.
关键词： epitaxial reactor cleaning,Chemical vapor deposition,chlorine trifluoride gas
更新于2025-09-19 17:15:36