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Plasmonic Sensing of Refractive Index and Density in Methanol-Ethanol Mixtures at High Pressure
摘要： The localized surface plasmon resonance (LSPR) of gold nanospheres dispersed in methanol-ethanol 4:1 was measured as a function of pressure up to 60 GPa. The LSPR exhibits an intense redshift with pressure in the range of 0-10 GPa, followed by a slower blueshift at higher pressures. This is because an increase in the solvent refractive index with pressure leads to a redshift of the LSPR peak wavelength while an increase in the electron density of the gold nanospheres with pressure leads to a blueshift. Solvent solidification at 10 GPa and associated non-hydrostatic effects have a negligible influence on the LSPR shifts in the case of nanospheres. Here we show that both the LSPR shifts and changes in the nanospheres absorption coefficient can be explained on the basis of Gans’ model, and this enables the solvent refractive index and the density of the solvent to be determined across the hydrostatic pressure range from 0-60 GPa. Interestingly, plasmonic sensing shows no evidence of crystallization or glass phase transitions in MeOH-EtOH (4:1) solvents within the explored pressure range.
关键词： High Pressure,Optical,Hybrid Materials,Methanol-Ethanol Mixtures,Density,Plasmonics,Magnetic,Refractive Index
更新于2025-09-23 15:21:01
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Laser-Induced Dissociation of the Monolayer of Adsorbed Methanol Molecules
摘要： Astronomical observations indicate a high abundance of methanol molecules in the gas phase of molecular-cloud dense cores, which cannot be explained by gas-phase chemical reactions only. A significant contribution to the methanol abundance should be provided by chemical reactions on the dust particle surface with subsequent desorption of the produced molecules into the gas phase. For the development and refinement of models involving these processes, laboratory studies of photo-induced processes occurring in the adsorbed material are necessary. In this paper, the experiment results of adsorbed methanol molecules are presented. A methanol molecule monolayer, physically adsorbed on fused silica surface cooled by liquid nitrogen (Т ～ 100 K), was irradiated in high vacuum by nanosecond pulses of an excimer KrF laser with a fixed wavelength λ = 248 nm. The photodissociation products of three-photon laser excitation were recorded by a quadrupole mass spectrometer. Relative yields of photofragments H, OH, and CH3 were determined. Photolysis of partially deuterated CH3OH molecules has shown that hydrogen atoms can be ejected both from hydroxyl and methyl groups. In contrast to the isolated molecule photolysis in the gas phase and dissociation of the multilayer molecular coatings, photoexcitation of adsorbed methanol monolayer even in the energy region of 10 eV does not cause noticeable chemical transformations and does not lead to the formation of molecular components H2 and CH4. Due to existing astrochemical modeling problems, possible application methods of the obtained laboratory results are considered.
关键词： chemical reactions,astronomical observations,adsorbed monolayer,mass spectrometry,photo-induced processes,gas phase,dust particle surface,KrF laser,photodissociation,methanol
更新于2025-09-23 15:21:01
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Deuterium Kinetic Isotope Effect in the Photocatalyzed Dissociation of Methanol on TiO2(110)
摘要： Deuterium kinetic isotope effect (KIE) in the photochemistry of methanol on TiO2(110) has been studied to find the rate-determining step (RDS) and understand the reaction mechanism using two-photon photoemission spectroscopy (2PPE). Deuterium substitution of the methyl hydrogen has little effect on the kinetics of this reaction, suggesting that neither the break of the C-H(D) bond nor the transfer of H(D) atoms to the bridging sites is the RDS in the transformation of methanol into formaldehyde. In contrast, the reaction rate of MeOH is ~1.3 times of that of MeOD, suggesting that the cleavage of O-H(D) is the RDS in the photocatalyzed dissociation of methanol on TiO2(110). The results contradict with the common fact that C-H(D) is more difficult to break than O-H(D) based on ground state energetics, implying the involvement of photogenerated charge carriers in the reaction of C-H break whereas the cleavage of O-H is likely a thermal reaction. Difference in the activation energy of O-H and O-D dissociation reaction in the methanol/TiO2(110) system has been calculated based on the KIE measurements. Our work is consistent with the fact that methoxy is photocatalytically more reactive than methanol, and suggests that the conversion of methanol into methoxy is crucial in the photochemistry of methanol on TiO2(110) and probably other metal oxide semiconductor surfaces.
关键词： two-photon photoemission spectroscopy,photocatalyzed dissociation,Deuterium kinetic isotope effect,TiO2(110),methanol
更新于2025-09-23 15:21:01
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A dual fuel microfluidic fuel cell utilizing solar energy and methanol
摘要： Methanol is a volatile fuel which can be fed into micro?uidic fuel cells in vaporized form. However, the methanol oxidation reaction is relatively sluggish compared with the hydrogen oxidation reaction. Therefore, a novel dual fuel micro?uidic fuel cell system powered by both methanol and methanol-derived hydrogen via photocatalysis is developed, which can achieve much improved cell performance while eliminating the hydrogen transportation, storage and safety issues. Pt/P25 is adopted as the photocatalyst which photo-reforms the methanol to hydrogen in the fuel tank. The intermediate during the photoreforming process can also be fed into the micro?uidic fuel cell as a fuel. Di?erent cell performance can be achieved by varying the fuel-water mix ratios in the tank. By optimizing the ratio, the peak power density can be increased by more than 10 times when the system is exposed to simulated solar light (3 suns) illumination.
关键词： Micro?uidic fuel cell,Methanol,Hydrogen,Photocatalysis,Mixed potential
更新于2025-09-23 15:21:01
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Why and how carbon dioxide conversion to methanol happens on functionalized semiconductor photoelectrodes
摘要： Functionalization of semiconductor electrode surfaces with adsorbed 2-pyridinide (2-PyH–*) has been postulated to enable selective CO2 photo-electro-reduction to CH3OH. This hypothesis is supported by recent estimates of sufficient 2-PyH–* lifetimes and low barriers for hydride transfer (HT) to CO2. However, the complete mechanism for reducing CO2 to CH3OH remained unidentified. Here, vetted quantum chemistry protocols for modeling GaP reveal a pathway involving HTs to specific CO2 reduction intermediates. Predicted barriers suggest that HT to HCOOH requires adsorbed HCOOH* reacting with 2-PyH–*, a new catalytic role for the surface. HT to HCOOH* produces CH2(OH)2 but subsequent HT to CH2(OH)2 forming CH3OH is hindered. However, CH2O, dehydrated CH2(OH)2, easily reacts with 2-PyH–* producing CH3OH. Further reduction of CH3OH to CH4 via HT from 2-PyH–* encounters a high barrier, consistent with experiment. Our finding that the GaP surface enables HT to HCOOH* explains why the primary CO2 reduction product over CdTe photoelectrodes is HCOOH rather than methanol, as HCOOH does not adsorb on CdTe and so the reaction terminates. The stability of 2-PyH–* (vs. its protonation product DHP*), the relative dominance of CH2(OH)2 over CH2O, and the required desorption of CH2(OH)2* are the most likely limiting factors, explaining the low yield of CH3OH observed experimentally.
关键词： hydride transfer,CO2 reduction,semiconductor,photoelectrodes,methanol
更新于2025-09-23 15:21:01
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On the processes of photo-induced hydrogen generation from methanol solution by Ta3N5 and?WO3
摘要： The hydrogen production rates from deionized water and 20% methanol solution, with or without the presence of Ta3N5, WO3, and the indirect Z-scheme Ta3N5/WO3, were investigated. Under irradiation of a 300 W Xe lamp, all of these three catalysts assisted hydrogen generation in deionized water. In the methanol solution, Ta3N5, and WO3 reduced the hydrogen generation, but Ta3N5/WO3 signi?cantly enhanced the hydrogen production rate by seven times. Under visible light irradiation, the effects of the three catalysts are different from those under full spectrum irradiation. The mechanisms based on the competition of methanol decomposition and water reduction in the presence of catalyst under different irradiation conditions are proposed to explain the different hydrogen generation behaviors.
关键词： WO3,Sacri?cial reagent,Photocatalytic hydrogen evolution,Methanol,Ta3N5
更新于2025-09-23 15:21:01
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Spectral filtering of photovoltaic cells using novel bio-filter: Silver coated Hibiscus extract using methanol solution
摘要： Spectra filtering is a fairly new concept to control the damaging contributions of solar IR radiations to photovoltaic (PV) cells or panel. In this research, the bio-filter was synthesized and tested. The bio-filter was proposed as the panacea to filtering the solar IR radiations. The bio-filter performance was adjudged to show little success, as it was 3% lower than the normal performance in the monocrystalline solar PV panel and 50% higher than the normal performance in the polycrystalline solar PV panel. The varying results in the polycrystalline and monocrystalline PV panels may arise as a result of unequal coating of the panel. Hence, the coating technique is recommended to be uniform and precise in further research work.
关键词： bio-filter,Hibiscus extract,photovoltaic cells,methanol solution,spectral filtering
更新于2025-09-23 15:19:57
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Photoelectrocatalytic oxidation of methanol over RuO2MnO2Co3O4 supported porous anatase under visible light irradiation
摘要： Anatase supported heterogeneous photocatalyst consisting of RuO2, MnO2 and Co3O4 (1:13:13 ratio) was synthesized by a precipitation method and tested for photoelectrocatalytic (PEC) oxidation of methanol in 0.1 M KOH under visible light irradiation. The as-prepared photocatalyst was characterized by FTIR, UV-vis, XRD, Raman spectroscopy, FESEM/EDX, TEM, BET, XPS and TPR. The PEC studies by cyclic voltammetry indicated that the oxidation of methanol to CO2 and H2O upon exposure to visible light occurs between 400 to 800 nm. The smaller value of the charge transfer resistance (Rct) of the RuO2-MnO2-Co3O4 supported anatase TiO2 electrode indicates a faster rate of charge transfer at the electrode-electrolyte interface compared to the Pt/C catalyst, which could be promising for direct methanol fuel cell application.
关键词： methanol,Titania,photoelectrocatalyst,photoelectrooxidation
更新于2025-09-23 15:19:57
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Is methanol a dopant under atmospheric pressure photoionization conditions?
摘要： Using a modified atmospheric pressure photoionization (APPI) source coupled to a tunable vacuum ultraviolet source at the SOLEIL synchrotron radiation facility, we determined the appearance energy of protonated methanol monomer and dimers at different source temperatures. The experimental data indicated that protonated monomers can be formed through the direct photoionization of neutral methanol by the second emission band of a krypton discharge UV lamp at 116.49 nm (10.64 eV) explaining why methanol can be considered as a weak dopant under APPI conditions. This point is in contradiction with the previously proposed mechanism where photoionization of methanol dimer was followed by the dissociation of the protonated methanol dimer into protonated methanol monomer.
关键词： dopant,synchrotron,ionization process,methanol,Atmospheric pressure photoionization
更新于2025-09-19 17:15:36
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A solid-state supramolecular hybrid complex based on dimethylammonium ions and silicon molybdate: Crystal structure, photochromic properties and catalytic performance
摘要： A novel organic-inorganic hybrid supramolecular Complex (C2H8N)4SiMo12O40 based on Keggin building blocks has been successfully synthesized by solvothermal method. Single-crystal X-ray analysis revealed that it crystallized in orthorhombic system, Pnma space group. The supramolecular crystalline network is formed via intermolecular hydrogen bonds. The target product was characterized by Infrared spectrum, thermogravimetric-differential thermal, cyclic voltammetry and fluorescent spectrum. Results prove that Complex emits blue fluorescence and has irreversible photochromic properties. Differential thermal-thermogravimetric and cyclic voltammetry shows that Complex has high thermal stability and strong oxidizability. The catalytic performances of Complex were investigated by solid-gas heterogeneous catalysis method. Using solid target product as catalyst, the catalyze degradation of methanol was tested in the temperature range from rt. to 160 °C. When the system flow rate is 5.0 mL min?1, initial concentration of methanol is 5.34 g m?3, reaction temperature is 150 °C, eliminating rate of methanol is 76%, those indicate that Complex has good catalytic activity.
关键词： Keggin structure,Polyoxometalates,Catalytic elimination,Methanol,Organic-inorganic hybrid
更新于2025-09-19 17:15:36