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Zinc Rhodium Oxide and Its Possibility as a Constituent Photocatalyst for Carbon Dioxide Reduction using Water as an Electron Source
摘要： We evaluated the potential of zinc rhodium oxide (ZnRh2O4) as a carbon dioxide (CO2) reduction photocatalyst with the aid of triethanolamine (TEOA) as an electron donor and demonstrated that ZnRh2O4 was able to reduce CO2 to carbon monoxide (CO) under infrared light. Gold (Au) loading onto ZnRh2O4 greatly enhanced the CO2 reduction activity. Also, CO2 reduction was examined over a composite of ZnRh2O4 and bismuth vanadium oxide (Bi4V2O11) with inserted Au (ZnRh2O4/Au/Bi4V2O11) using H2O as the electron source, which led to the successful evolution of CO.
关键词： Carbon monoxide,Methane,Triethanolamine,Gold,Carbon dioxide reduction,Zinc rhodium oxide
更新于2025-11-19 16:51:07
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Enhanced Methane Sensing Properties of WO3 Nanosheets with Dominant Exposed (200) Facet via Loading of SnO2 Nanoparticles
摘要： Methane detection is extremely difficult, especially at low temperatures, due to its high chemical stability. Here, WO3 nanosheets loaded with SnO2 nanoparticles with a particle size of about 2 nm were prepared by simple impregnation and subsequent calcination using SnO2 and WO3·H2O as precursors. The response of SnO2-loaded WO3 nanosheet composites to methane is about 1.4 times higher than that of pure WO3 at the low optimum operating temperature (90 °C). Satisfying repeatability and long-term stability are ensured. The dominant exposed (200) crystal plane of WO3 nanosheets has a good balance between easy oxygen chemisorption and high reactivity at the dangling bonds of W atoms, beneficial for gas-sensing properties. Moreover, the formation of a n–n type heterojunction at the SnO2-WO3 interface and additionally the increase of specific surface area and defect density via SnO2 loading enhance the response further. Therefore, the SnO2-WO3 composite is promising for the development of sensor devices to methane.
关键词： methane sensing,SnO2-loaded WO3 nanosheets,exposed (200) facet,heterojunction
更新于2025-11-14 17:03:37
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Efficient Conversion of CO <sub/>2</sub> to Methane Photocatalyzed by Conductive Black Titania
摘要： One of the major challenges encountered in CO2 utilization is the development of available and cost-efficient catalysts with sufficient activity, selectivity, and stability for the generation of useful methane. Here, conductive black titania, TiO2@x, is found to be efficient in photocatalyzing the reduction of CO2 to CH4. This unique material comprises a crystalline core–amorphous shell structure (TiO2@TiO2@x) with numerous surface oxygen vacancies, which facilitates the adsorption and chemical activation of CO2 molecules. Under full solar irradiation, the optimized 500-TiO2@x material with narrowed band gap and intermediate states below the conduction band tail exhibits a high space-time yield of CH4 of 14.3 mmol g@1 h@1, with 74 % selectivity and excellent photostability. The present findings can make a significant contribution, not only to develop the surface electron-modified black TiO2 catalyst to boost photocatalytic efficiency, but also to establish a really viable and convenient CH4 production process for CO2 conversion and renewable solar energy storage.
关键词： oxygen vacancies,photocatalysis,carbon dioxide chemistry,conductive black titania,methane generation
更新于2025-09-23 15:23:52
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{μ-Bis(diphenylphosphino)methane}(1-alkyl-2-(arylazo)imidazole) copper(I) perchlorate : Synthesis, Structure and Photochromism
摘要： 1-Alkyl-2-(arylazo)imidazole (RaaiR/), a bidentate N(azo), N(imidazolyl) chelator, and bis(diphenylphosphino)methane (dppm), a P, P bridger, have been used to prepare phosphino bridged dinuclear-Cu(I) complexes, [Cu(μ-dppm)(RaaiR/)]2(ClO4)2. The structures of the complexes have been established by spectral (UV-Vis, IR, 1H-NMR) data and the confirmation has been done in case of [Cu(μ-dppm)(HaaiEt)]2(ClO4)2 by single crystal X-ray diffraction studies. Optical stimulation using UV light (365 nm) in methanol solution of the complexes shows that the coordinated RaaiR/ undergoes trans-to-cis isomerization about –N=N-Ar. The rate of trans-to-cis isomerization varies 1.11×10-8 - 1.89×10-8 s-1 and is largely dependent on mass of the photochrome and strain/steric crowding generated about –N=N- bond. Quantum yields (φt→c) of trans-to-cis isomerization, 0.0843 – 0.1421, are calculated and free ligand shows higher φ (0.17 – 0.26) than their complex phase. The cis-to-trans isomerisation is a thermally induced process. The activation energy (Ea) of cis-to-trans isomerisation is calculated by controlled temperature experiment and is found that Ea (ligands) > Ea (complexes).
关键词： photochromism.,Copper (I) complexes,bis-(diphenylphosphino)methane,Arylazoimidazole,spectral study
更新于2025-09-23 15:23:52
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Optimised Performance of Non-Dispersive Infrared Gas Sensors Using Multilayer Thin Film Bandpass Filters
摘要： In this work, performance improvements are described for a low-power consumption non-dispersive infrared (NDIR) methane (CH4) gas sensor using customised optical thin film bandpass filters (BPFs) centered at 3300 nm. BPFs shape the spectral characteristics of the combined mid-infrared III–V based light emitting diode (LED)/photodiode (PD) light source/detector optopair, enhancing the NDIR CH4 sensor performance. The BPFs, deposited using a novel microwave plasma-assisted pulsed DC sputter deposition process, provide room temperature deposition directly onto the temperature-sensitive PD heterostructure. BPFs comprise germanium (Ge) and niobium pentoxide (Nb2O5) alternating high and low refractive index layers, respectively. Two different optical filter designs are progressed with BPF bandwidths (BWs) of 160 and 300 nm. A comparison of the modelled and measured NDIR sensor performance is described, highlighting the maximised signal-to-noise ratio (SNR) and the minimised cross-talk performance benefits. The BPF spectral stability for various environmental temperature and humidity conditions is demonstrated.
关键词： III–V,sensor,methane,thin film,MBE,NDIR,microwave,bandpass,sputter,heterostructure,infrared
更新于2025-09-23 15:23:52
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Sequential activation of methane by Ir+: An IRMPD and theoretical investigation
摘要： The sequential activation of up to 4 CH4 molecules by Ir+ is investigated through a gas-phase infrared multiple photon dissociation (IRMPD) experiment and theoretical calculations. A molecular beam apparatus was used to generate Ir+ by laser ablation and expose it to controlled amounts of CH4. Product ions were irradiated with IR light from a free electron laser over the 500–1800 cm?1 spectral range and photodissociation was monitored using a time-of-flight mass spectrometer. Experimental spectra were obtained for five distinct species: [Ir,3C,8 H]+, [Ir,3C,10 H]+, [Ir,4C,10 H]+, [Ir,4C,12 H]+, and [Ir,O,3C,12 H]+. To identify these species, B3LYP/def2-TZVPPD geometry optimizations were performed on a variety of possible structures, with computed IR spectra compared to the experimental IRMPD spectra. This has led to the following assignments: [Ir,3C,8 H]+ = IrCH2(CH3)2+, [Ir,3C,10 H]+ = HIr(CH3)3+, [Ir,4C,10 H]+ = Ir(CH3)2(C2H4)+, [Ir,4C,12 H]+ = a mixture of HIr(CH3)(C2H4)+(CH4), HIr(CH3)2(C2H5)+, Ir(CH3)4+, and (H2)Ir(CH3)2(C2H4)+, and [Ir,O,3C,12 H]+ = (H2O)HIr(CH3)3+. Notably, evidence for C C coupling is observed upon reaction with a fourth methane. Mechanisms for the formation of the observed products were also explored computationally by examining the reaction coordinate pathways for the reactions of methane with HIrCH+, IrCH2+, Ir(CH3)2+, HIrCH2(CH3)+, HIr(CH3)3+, and IrCH2(CH3)2+.
关键词： Iridium,Carbon-carbon coupling,Methane activation,Dehydrogenation,Infrared multiple photon dissociation,Reaction coordinate pathway
更新于2025-09-23 15:22:29
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Continuous in situ measurement of dissolved methane in Lake Kivu using a membrane inlet laser spectrometer
摘要： We report the ?rst high-resolution continuous pro-?le of dissolved methane in the shallow water of Lake Kivu, Rwanda. The measurements were performed using an in situ dissolved gas sensor, called Sub-Ocean, based on a patented membrane-based extraction technique coupled with a highly sensitive optical spectrometer. The sensor was originally designed for ocean settings, but both the spectrometer and the extraction system were modi?ed to extend the dynamical range up to 6 orders of magnitude with respect to the original prototype (from nmol L?1 to mmol L?1 detection) to ?t the range of concentrations at Lake Kivu. The accuracy of the instrument was estimated to ±22 % (2σ ) from the standard deviation of eight pro?les at 80 m depth, corresponding to ±0.112 mbar of CH4 in water or ±160 nmol L?1 at 25 ?C and 1 atm. The instrument was able to continuously pro?le the top 150 m of the water column within only 25 min. The maximum observed mixing ratio of CH4 in the gas phase concentration was 77 %, which at 150 m depth and under thermal conditions of the lake corresponds to 3.5 mmol L?1. Deeper down, dissolved CH4 concentrations were too large for the methane absorption spectrum to be correctly retrieved. Results are in good agreement with discrete in situ measurements conducted with the commercial HydroC? sensor. This fast-pro?ling feature is highly useful for studying the transport, production and consumption of CH4 and other dissolved gases in aquatic systems. While the sensor is well adapted for investigating most environments with a concentration of CH4 up to a few millimoles per liter, in the future the spectrometer could be replaced with a less sensitive analytical technique possibly including simultaneous detection of dissolved CO2 and total dissolved gas pressure, for exploring settings with very high concentrations of CH4 such as the bottom waters of Lake Kivu.
关键词： Lake Kivu,dissolved methane,membrane inlet laser spectrometer,Sub-Ocean sensor,HydroC? sensor
更新于2025-09-23 15:21:01
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Evanescent field ratio enhancement of a modified ridge waveguide structure for methane gas sensing application
摘要： We presented a significant improvement of the evanescent field ratio in a ridge waveguide modified into a dual hybrid plasmonic waveguide by tapering the middle section of the waveguide and placing a gold layer on both sides with a sub-wavelength gap. The waveguide geometry is optimized at 3.392 μm which is an absorption line of methane gas. The proposed waveguide scheme provides a large waveguide cross-section which facilitates a light with an enhanced evanescent field in the middle. To validate the study, the evanescent field ratio, propagation loss, confinement factor and electric field distribution of the waveguide is studied via the finite element method. Additionally, the device is also proposed. An elevated evanescent field ratio of 0.74 is obtained with a propagation loss of ~0.7 dB/μm. The sensitivity of 0.0715 (mW/gas conc.) is obtained for the proposed waveguide scheme by calculating the decay in transmission power due to absorption by the gas in the medium.
关键词： Evanescent field absorption gas sensor,3.392 μm,methane,mid-infrared,Lambert-Beer law
更新于2025-09-23 15:21:01
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Online fire protection technology based on fiber optic gas sensor
摘要： In recent years, the production safety has been paid by a lot of attention. Although the total number of accidents in production safety has shown a downward trend, the serious accidents occur frequently and seriously. The prediction and early warning of spontaneous combustion in coal mines mainly adopts the method of gas index analysis and prediction. The traditional trace gas detection equipment used in spontaneous combustion is mainly chromatographic analysis system, which has some problems such as complicated equipment, complicated operation, slow analysis speed and inability to realize on-line monitoring. The main purpose of this study is to develop a fire risk distribution determination system based on multi-sensor information fusion technology, which is aimed at assisting fire monitoring, fire emergency management, and fire rescue. After using the information from different sensors, the system can give an effective alarm to the fire and can provide the danger degree distribution information of different areas in the building. Based on the development status of fire safety, especially the demand of fire safety for gas detection technology, the tunable laser spectroscopy technology is proposed to solve the demand problem of gas sensing products urgently needed for major fire disasters.
关键词： Optical Fiber,Fire Safety,Optical Fiber Methane Sensor,Multicomponent Gas Detection
更新于2025-09-23 15:21:01
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Accurate measurements of line strengths and air-broadening coefficients in methane around 1.66?μm using cavity ring down spectroscopy
摘要： Accurate measurements of line strengths and air-broadening coefficients for 10 lines of 12CH4 mostly from the band (2ν2 + ν3) and 2 lines of 13CH4 from the band (2ν3) around 1.66 μm were performed using cavity ring down spectroscopy. Spectra of mixtures of 12CH4 in air with well-defined mole fractions of methane were recorded at pressures between 10 and 90 mbar at 296 K. The values of the line strength for 12CH4 lines were obtained with the uncertainty 1% and 2%, respectively. The uncertainties of the values of the air-broadening coefficient varied from 2 to 5% depending on the line. The values of the line strength and air-broadening coefficient for two methane isotopes obtained in this work were compared with the corresponding values from different experimental studies, as well as with the data given in HITRAN 2016 database.
关键词： Line intensity measurements,Cavity ring down spectroscopy,Methane,Infrared,Air-broadening coefficients
更新于2025-09-23 15:21:01