- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Humidity effect on adsorption kinetics of ammonia onto electrospun SnO <sub/>2</sub> nanofibers
摘要： Tin dioxide nanofibers were successfully synthesized by electrospinning homogeneous solution of SnCl4·5H2O in polyvinyl alcohol (PVA) and the potential of SnO2 nanofibers as ammonia sensing element at room temperature were also investigated. A logarithmic dependence of sensitivity on ammonia concentration was observed. We further investigate the effect of relative humidity between 0% and 70% on ammonia sensing performance of SnO2 nanofibers based conductometric sensor for the first time. Sensing experiments showed that both the baseline sensor current and the response-recovery characteristics of the SnO2 based sensor modified by pre humidification of sensing layer' surface. To study the adsorption kinetics pseudo first order and Elovich models was used and the first order kinetic model best describes the ammonia adsorption onto the SnO2 nanofibers for low concentrations (≤80 ppm) of ammonia, irrespective of humidity level. On the other hand, the results describe the best representation of Elovich model, as evidenced by the high correlation coefficients, for high concentrations of ammonia gas.
关键词： adsorption kinetics,humidity effect,ammonia sensing,electrospinning,response time
更新于2025-09-23 15:22:29
-
Orthogonal gas sensor arrays by chemoresistive material design
摘要： Gas sensor arrays often lack discrimination power to different analytes and robustness to interferants, limiting their success outside of research laboratories. This is primarily due to the widely sensitive (thus weakly-selective) nature of the constituent sensors. Here, the effect of orthogonality on array accuracy and precision by selective sensor design is investigated. Therefore, arrays of (2–5) selective and non-selective sensors are formed by systematically altering array size and composition. Their performance is evaluated with 60 random combinations of ammonia, acetone and ethanol at ppb to low ppm concentrations. Best analyte predictions with high coefficients of determination (R2) of 0.96 for ammonia, 0.99 for acetone and 0.88 for ethanol are obtained with an array featuring high degree of orthogonality. This is achieved by using distinctly selective sensors (Si:MoO3 for ammonia and Si:WO3 for acetone together with Si:SnO2) that improve discrimination power and stability of the regression coefficients. On the other hand, arrays with collinear sensors (Pd:SnO2, Pt:SnO2 and Si:SnO2) hardly improve gas predictions having R2 of 0.01, 0.86 and 0.28 for ammonia, acetone and ethanol, respectively. Sometimes they even exhibited lower coefficient of determination than single sensors as a Si:MoO3 sensor alone predicts ammonia better with a R2 of 0.68.
关键词： Ethanol,WO3,SnO2,Electronic nose,Ammonia,Gas sensor,Acetone,Flame spray pyrolysis,MoO3
更新于2025-09-23 15:21:21
-
Exergoeconomic analysis and optimization of a concentrated sunlight-driven integrated photoelectrochemical hydrogen and ammonia production system
摘要： The study presented here concerns a comprehensive investigation on exergoeconomic analysis and optimization of an integrated system for photoelectrochemical hydrogen and electrochemical ammonia production. The present integrated system consists of a solar concentrator, spectrum-splitting mirrors, a photoelectrochemical hydrogen production reactor, a photovoltaic module, an electrochemical ammonia production reactor and support mechanisms. Detailed thermodynamic and exergoeconomic analyses are initially conducted to determine the performance of the integrated system namely; efficiency and total cost rate. The obtained performance parameters are then optimized to yield the minimum cost rate and maximum efficiency under given constraints of the experimental system. The highest capital cost rates are observed in the photoelectrochemical hydrogen and electrochemical ammonia production reactors because of high procurement costs and electricity inputs. The optimized values for exergy efficiency of the integrated system range from 5% to 9.6%. The photovoltaic and photoelectrochemical cell areas and solar light illumination mainly affect the overall system efficiencies. The optimum efficiencies are found to be 8.7% and 5% for the multi-objective optimization of hydrogen production and integrated ammonia production system, respectively. When the exergy efficiency of the integrated system is maximized and the total cost rate is minimized at the same time, the total cost rate of the system is calculated to be about 0.2 $/h. The cost sensitivity analysis results of the present study show that the total cost rate of the system is mostly affected by the interest rate and lifetime of the system.
关键词： Exergoeconomics,Solar energy,Hydrogen,Optimization,Photoelectrochemical process,Ammonia
更新于2025-09-23 15:21:21
-
Surfactant-free Exfoliation of Multilayer Molybdenum Disulfide Nanosheets in Water
摘要： In this study, we report a potentially scalable method for producing multilayer molybdenum disulfide (MoS2) nanosheets. The addition of a small amount of ammonia solution can improve the exfoliation of MoS2 nanosheets in water. The surface charge induced by spontaneous adsorption of hydroxyl ions on MoS2 surfaces favors the exfoliation process. The edge charge generated by the ionization of edge-attached groups facilities the dispersion of exfoliated nanosheets in water. It is also found that smaller MoS2 nanosheets show an improved photocatalytic performance, which stems from enhanced edge effects and a reduced flake thickness. This work opens a new vista on preparation and application of multilayer MoS2 nanosheets.
关键词： edge effects,ammonia solution,dispersion,water,multilayer MoS2 nanosheets,exfoliation
更新于2025-09-23 15:21:21
-
Determining Plasmonic Hot Electron and Photothermal Effects during H <sub/>2</sub> Evolution with TiN-Pt Nanohybrids
摘要： Hydrogen storage in chemical compounds is a promising strategy to enable lightweight, high density, and safe hydrogen technologies. However, the hydrogen release rate from these chemicals is limited by the intrinsic catalytic activity of metal catalysts, which can be enhanced by using light irradiation. Here nanohybrids including a core of plasmonic TiN and multiple Pt nanocrystal catalytic centers are assembled and show, under resonant conditions at 700 nm, hot electrons driven hydrogen evolution from ammonia borane at an apparent quantum yield of 120%. It is also demonstrated that solar irradiation enhances the activity of TiN-Pt nanohybrids by one order of magnitude through two synergistic mechanisms: the hot electrons and collective-heating contributions. Using the microscopic calculation of the photoinduced temperature around a single nanocrystal, it is revealed that the collective plasmonic heating regime dominates the macroscopic temperature distribution in the system. The presented data show that plasmonic hot electrons and photothermal heating can be used in synergy to trigger hydrogen release from ammonia borane on demand, providing a general strategy for greatly enhancing the activity in the dark of metal catalysts.
关键词： ammonia-borane,plasmonics,photocatalysis,titanium nitride,hydrogen evolution
更新于2025-09-23 15:21:01
-
Reduced graphene oxide hybridized with WS2 nanoflakes based heterojunctions for selective ammonia sensors at room temperature
摘要： Hybrid of the two dimensional nanostructured reduced graphene oxide (rGO) and WS2 has been investigated for a room temperature ammonia sensor. The formed rGO/WS2 heterojunctions prepared by one-step hydrothermal synthesis indicated a good sensitivity to different concentrations of ammonia from 10 ppm to 50 ppm at room temperature. The WS2 nanoflakes doped in the heterojunction plays significant role in the enhanced response through the introduction of more hydroxyls in rGO and the extra Lewis acid active centers. The sensor also shows an excellent selectivity to NO2, alcohols, formaldehyde，acetone and benzene and a good long term stability indicating a potential to be employed as a room temperature NH3 sensor.
关键词： rGO/WS2 heterojunctions,Room Temperature,Ammonia Sensors
更新于2025-09-23 15:21:01
-
Liquid phase exfoliation of MoS2 and WS2 in aqueous ammonia and their application in highly efficient organic solar cells
摘要： Simple, scalable and cost-effective synthesis of quality two-dimensional (2D) transition metal dichalcogenides (TMDs) is critical for fundamental investigations but also for the widespread adoption of these low-dimensional materials to an expanding range of device applications. Here, we report on the liquid-phase exfoliation (LPE) of molybdenum disulfide (MoS2) and tungsten disulfide (WS2) in aqueous ammonia (NH3 (aq)) as a greener alternative to commonly used but less environmentally friendly solvents. The synthesized nanosheets can be prepared in high concentrations (0.5-1 mg mL-1) and exhibit excellent stoichiometric and structural quality with a semiconducting character. These characteristics makes them ideal for application in organic optoelectronics, where optical transparency and suitable energetics are two important prerequisites. When MoS2 and WS2 are used as the sole hole transport layer materials in organic photovoltaics, cells with power conversion efficiency of 14.9 and 15.6%, respectively, are obtained highlighting the potential of the aqueous ammonia-based LPE method for the preparation of high quality TMDs. The method could potentially be extended to other TMDs.
关键词： aqueous ammonia,MoS2,liquid-phase exfoliation,organic solar cells,WS2
更新于2025-09-23 15:19:57
-
Deeply cooled and temperature controlled microjets: Liquid ammonia solutions released into vacuum for analysis by photoelectron spectroscopy
摘要： A versatile, temperature controlled apparatus is presented, which generates deeply cooled liquid microjets of condensed gases, expelling them via a small aperture into vacuum for use in photoelectron spectroscopy (PES). The functionality of the design is demonstrated by temperature- and concentration-dependent PES measurements of liquid ammonia and solutions of KI and NH4I in liquid ammonia. The experimental setup is not limited to the usage of liquid ammonia solutions solely.
关键词： NH4I,KI,liquid microjets,liquid ammonia,temperature control,photoelectron spectroscopy
更新于2025-09-23 15:19:57
-
Temperature dependent control of the solubility of gallium nitride in supercritical ammonia using mixed mineralizer
摘要： Using a mass-loss method, we investigated the solubility change of gallium nitride (GaN) in supercritical ammonia with mixed mineralizers [ammonium chloride (NH4Cl) + ammonium bromide (NH4Br) and NH4Cl + ammonium iodide (NH4I)]. The solubilities were measured over the temperature range 450–550 °C, at 100 MPa. The solubility increased with NH4Cl mole fraction at 450 °C and 100 MPa. The temperature dependence of the solubility curve was then measured at an equal mole ratio of the two mineralizers. The slope of the solubility–temperature relationship in the mixed mineralizer was between those of the individual mineralizers. These results show that the temperature dependence of the solubility of GaN can be controlled by the mineralizer mixture ratio. The results of the van’t Hoff plot suggest that the solubility species were unchanged over the investigated temperature range. Our approach might pave the way to realizing large, high-quality GaN crystals for future gallium-nitride electronic devices, which are increasingly on demand in the information-based age.
关键词： Acidic mineralizer,Gallium nitride,Ammonothermal,Solubility,Supercritical ammonia
更新于2025-09-19 17:15:36
-
Graphene materials as a superior platform for advanced sensing strategies against gaseous ammonia
摘要： Ammonia (NH3) is an uncolored, toxic, corrosive, and reactive gas with a characteristic pungent stench. To date, quantitative analysis of NH3 concentrations have been made using conventional techniques (e.g., ion chromatography). In light of the complications involved in such applications, efforts have been made to develop detection methods of NH3 that are more sensitive and selective. In this respect, graphene-based sensors have attracted widespread attention because of graphene's distinctive electrical characteristics (e.g., low electrical signal noise and great mobility) and large surface area. This review article was designed to evaluate the potential usage of graphene-based gas sensors for effective detection of NH3. We aim to understand the recent advances in this challenging area of research by critically analyzing various experiments and comprehending their practical implications. This review critically compares the performance of graphene-based NH3 sensors with those of other nanomaterials for a broader understanding of the field. Also, we summarize the future prospects for advancement of graphene technology for NH3 sensing.
关键词： graphene,ammonia sensing,nanomaterials,electrochemical sensing,gas sensors
更新于2025-09-19 17:15:36