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Solar–gliding arc plasma reactor for carbon dioxide decomposition: Design and characterization
摘要： The conversion of low-value feedstock such as carbon dioxide (CO2) into higher-value products using renewable energy, particularly solar, can help fulfill the increasing need for fuels and chemicals while mitigating environmental emissions. A direct solar receiver-reactor fitted with a gliding arc (glidarc) electrical discharge for potentially greater efficiency and continuous operation solar thermochemical synthesis is presented. The nonequilibrium plasma inside the reactor chamber leads to increased solar energy absorption by the gas-phase feedstock, potentially enhancing chemical conversion. Moreover, the reliance on electrical energy to sustain the plasma allows compensating for fluctuations in the solar radiation input. Two solar-glidarc reactor configurations are investigated and evaluated for the decomposition of CO2 at atmospheric pressure conditions, namely: axi-radial (AXR) and reverse-vortex (RVX) flow. The former provides greater control of residence time but presents limited solar-plasma interaction; whereas the latter allows for greater interaction, but requires higher flow rates to confine the plasma, lowering the residence time. Flow paths and residence times are evaluated via Computational Fluid Dynamics (CFD) models used to guide reactor design and operation. Evaluation of the plasma volume at different reactor orientations, aimed to mimic in-field operation, show that the AXR configuration leads to a larger plasma volume compared to that by the RVX design. Net-absorption tests, aimed to assess the extent of solar-plasma interaction, showed up to 18% net-absorption of solar radiation for the RVX configuration and 7% for the AXR one, compared to 0% in the absence of plasma. The AXR configuration, despite its lower absorption of solar energy, leads to greater CO2 homogeneous gas-phase decomposition (i.e. in the absence of any catalyst), of up to 4.5%, mainly due to its flexibility in operating with lower residence times. The results indicate solar-plasma direct-receiver reactors provide a compelling approach to solar thermochemical synthesis processes.
关键词： Chemical synthesis,Radiation absorption,Solar fuels,Atmospheric pressure nonequilibrium plasma,Solar receiver-reactor
更新于2025-09-19 17:15:36
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Low-cost uncooled MWIR PbSe quantum dots photodiodes
摘要： A mid-wave infrared (MWIR) uncooled PbSe-QDs/CdS p–n heterojunction photodiode has been fabricated using a wet-chemical synthesis route. This offers a low-cost alternative to traditional monocrystalline photodiodes relying on molecular beam epitaxy (MBE) technology. It was demonstrated that the post-annealing is critical to tailor the photoresponse wavelength and to improve the performance of photodiodes. After annealing at 673 K in air for 0.5 h, the ligand-free PbSe-QDs/CdS photodiode exhibits a MWIR spectral photoresponse with a cutoff wavelength of 4.2 mm at room temperature. Under zero-bias photovoltaic mode, the peak responsivity and specific detectivity at room temperature are 0.36 (cid:1) 0.04 A W(cid:3)1 and (8.5 (cid:1) 1) (cid:4)108 cm Hz1/2 W(cid:3)1, respectively. Temperature-dependent spectral response shows an abnormal intensity variation at temperatures lower than 200 K. This phenomenon is attributed to the band alignment transition from type II to type I, resulting from the positive temperature coefficient of PbSe. In addition, it was proved that In doped CdSe (CdSe:In) films could be used as a promising new candidate of infrared transparent conductive electrodes, paving the way for monolithic integration of uncooled low-cost MWIR photodiodes on Si readout circuitry.
关键词： infrared transparent conductive electrodes,MWIR,photodiode,CdSe:In,wet-chemical synthesis,PbSe-QDs,annealing
更新于2025-09-16 10:30:52
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Investigation on Surface Properties of Mn-Doped CdSe Quantum Dots Studied by X-ray Photoelectron Spectroscopy
摘要： In this work, we report on the effects of incorporating manganese (Mn) dopant into different sizes of cadmium selenide (CdSe) quantum dots (QDs), which improves the electronic and optical properties of the QDs for multiple applications such as light-emitting diodes, lasers, and biological labels. Furthermore, the greener inverse Micelle method was implemented using organic ligand, which is oleic acid. This binding of the surface enhanced the QDs’ surface trap passivation of Mn-doped CdSe, which then increased the quantity of the output. In addition, the inverse Micelle technique was used successfully to dope Mn into CdSe QDs without the risk of Mn dopants being self-purified as experienced by wurtzite CdSe QDs. Also, we report the X-ray photoelectron spectroscopy (XPS) results and analysis of zinc blended manganese-doped cadmium selenide quantum dots (Mn-doped CdSe QDs), which were synthesized with physical sizes that varied from 3 to 14 nm using the inverse Micelle method. The XPS scans traced the existence of the Se 3d and Cd 3d band of CdSe crystals with a 54.1 and 404.5 eV binding energy. The traced 640.7 eV XPS peak is proof that Mn was integrated into the lattice of CdSe QDs. The binding energy of the QDs was related to the increase in the size of the QDs.
关键词： quantum dots,semiconductor,chemical synthesis,cadmium selenide,X-ray photoelectron spectroscopy,manganese doped
更新于2025-09-16 10:30:52
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Thermal and laser sintering of a highly stable inkjet ink consisting of silver nanoparticles stabilized by a combination of a short chain carboxylic acid and a polymeric dispersant
摘要： A mixture of silver nanoparicles and its organic salt has been used for the development of conductive inks for inkjet printing. Silver nanoparticles stabilized with butanoic acid (C4) with the average size of 11.1±2.4 nm have been synthesized via the reduction of solid silver carboxylate with hydrazine hydrate in benzyl alcohol. An inkjet ink formulation consisting of the silver nanoparticles capped with butanoic acid (up to 50 wt.%) with the addition of polymeric BYK dispersant in a mixture of nontoxic solvents with different boiling temperatures and different polarities has been developed and its physical properties and stability have been studied. Silver layers were spin coated and printed on a polyimide film using the developed ink. Experiments on the thermal annealing of the silver films showed that the curing temperature can be below 200 oC to obtain a layer having the electrical resistivity less than 10 μ?×cm. A study of the laser sintering of the printed and spin coated elements on a polyimide film using a diode laser operating at 453 nm in impulse mode showed that the best mode is a multi-pass sintering, which can be divided into two steps: the evaporation of the solvent and sintering of the silver nanoparticles.
关键词： silver nanoparticles,selective laser sintering,conductive ink,chemical synthesis,printed electronics
更新于2025-09-12 10:27:22
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Green Phosphors Based on 9,10-bis((4-((3,7-dimethyloctyl)oxy) phenyl) ethynyl) Anthracene for LED
摘要： An anthracene aromatic unit was introduced into the phenylethynyl structure by a rigid acetylene linkage at the C-9 and C-10 positions via Sonogashira coupling reactions, resulting in a planar and straight-backbone molecule (9,10-bis((4-((3,7-dimethyloctyl)oxy) phenyl) ethynyl) anthracene) (BPEA). Thermogravimetric analysis demonstrated the good thermal stability of the BPEA. Photoluminescence analysis showed that a suitable expanded π-conjugation in the BPEA made its excitation band extend into the visible region, and an intense green emission was observed under blue-light excitation. A bright green light-emitting diode with an e?ciency of 18.22 lm/w was fabricated by coating the organic phosphor onto a 460 nm-emitting InGaN chip. All the results indicate that BPEA is a useful green-emitting material which is e?ciently excited by blue light, and therefore, that it could be applied in many ?elds without UV radiation.
关键词： chemical synthesis,bathochromic shift,luminescence,phosphors
更新于2025-09-11 14:15:04
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Handbook of Graphene || Self‐Assembled Thin Films of Graphene Materials for Sensors
摘要： It is well known that graphene and its derivatives exhibit unique optical, electrical, mechanical, and chemical properties, which are valuable for sensing applications. However, the chosen methods to synthesize and process graphene to form the sensing unit are critical steps defining the real property of the final sensor. Instead of a physical mixture of graphene in a bulk support, different immobilization techniques have been investigated to take advantage of the outstanding properties of graphene and graphene-based materials, such as linkage to the self-assembled monolayers, layer-by-layer, and Langmuir–Blodgett techniques. Such techniques lead to a new concept of nanoarchitectonics allowing to take a synergistic effect on mixing distinct properties with various materials in a unique device. Examples of these approaches on developing electrochemical, electric, and optical sensors are discussed in an overview.
关键词： chemical synthesis,self-assembled monolayers,Sensors,layer-by-layer,Langmuir–Blodgett,biosensors
更新于2025-09-11 14:15:04
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Improvement of charge transport for hydrothermally synthesized Cd0.8Fe0.2S over co-precipitation method: A comparative study of structural, optical and magnetic properties
摘要： Here, we have elucidated the structural, optical, magnetic and electrical properties of Cd0.8Fe0.2S which is considered as diluted magnetic semiconductor (DMS). Cd0.8Fe0.2S materials were synthesized using co-precipitation (compound 1) and hydrothermal (compound 2) method. The particle size and the polycrystalline phase of the synthesized materials are significantly influenced by the synthesis procedures. Presence of anti-ferromagnetic coupling confirms the magnetic behavior of materials. The current-voltage (I-V) characteristics exhibit lower barrier height for the device based on compound 2 (0.59 eV) than the other device (0.64 eV). Furthermore, the 19 times enhanced mobility and lesser density of states near the Fermi level for the Al/compound 2/ITO configured device is enlightened by the space charge conduction mechanism. But, the interface resistances of the devices cannot be distinguished by the I-V characteristics. Therefore, we have tackled the problem by simulating the Nyquist plots obtained from impedance spectroscopy. We have fitted the Nyquist plots with the appropriate equivalent circuit and explained the mechanism of charge transport through the Schottky interface. The higher dc conductivity and lower relaxation time of diode fabricated by compound 2 confirm the outcomes obtained from I-V characteristics. The effect of particle size on charge transport was also analyzed.
关键词： Schottky diode characteristics,Diluted magnetic semiconductor,Chemical synthesis,Impedance spectroscopy
更新于2025-09-10 09:29:36
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Dewetted nanostructures of gold, silver, copper, and palladium with enhanced faceting
摘要： At the foundation of nanoscience and nanotechnology is the ability to shape-engineer nanometric objects so as to exert control over their physical and chemical properties. Architectural control is achieved by manipulating thermodynamic and kinetic factors that are able to guide reactions along pathways that lead to the formation or elimination of particular crystal facets. While the dewetting of ultrathin metal films provides a straightforward method for generating substrate-based metallic nanostructures, the ability to shape-engineer these structures is limited to such an extent that even the formation of highly faceted equiaxed structures often proves challenging. This, however, is not the case for colloidal syntheses where the exquisite chemical controls and synthetic ease offered by liquid-phase chemistry has led to the generation of a diverse library of nanostructure architectures. Here, it is demonstrated that the faceting of dewetted structures of gold, silver, copper, and palladium can be enhanced by subjecting them to a liquid-phase chemical environment in which metal ions are reduced to a neutral state and deposited on the nanostructure surface in manner that leads to facet formation. The faceting procedure, which can be carried out in minutes, is also shown to be amenable to a templated dewetting approach in which lithographically-defined metal discs formed in an array each agglomerate to form a single nanostructure. The work has the potential to increase the functionality of dewetted nanostructures by enabling facet-dependent chemical reactivity and plasmonic hot spots.
关键词： tetrahexahedron,chemical synthesis,facets,thermal diffusion,epitaxial growth
更新于2025-09-09 09:28:46
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Structural Characterization of Two New Quaternary Chalcogenides: CuCo2InTe4 and CuNi2InTe4
摘要： The crystal structure of the chalcogenide compounds CuCo2InTe4 and CuNi2InTe4, two new members of the I-II2-III-VI4 family, were characterized by Rietveld refinement using X-ray powder diffraction data. Both materials crystallize in the tetragonal space group I 4 2m (No. 121), Z = 2, with a stannite-type structure, with the binaries CoTe and NiTe as secondary phases.
关键词： structural characterization,chemical synthesis,alloys,semiconductors,X-ray powder diffraction
更新于2025-09-09 09:28:46
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Towards understanding the enhancement of antibacterial activity in manganese doped ZnO nanoparticles
摘要： In this work we focus on enhancing the antibacterial activity of ZnO nanoparticles by Mn doping, synthesized using a wet-chemical method. The as-obtained precursor powders were deeply investigated by thermal analyses correlated with the evolved gas analysis (TG-DTA-FT-IR) and by in situ high-temperature XRD to elucidate the thermally induced processes and to understand the manganese doped ZnO nanoparticles formation. The hexagonal wurtzite-type structure and the morphological characteristics of the thermally treated samples have been investigated by X-ray diffraction, and HRTEM. An average particle size ranging between 10 to 29 nm and a polyhedral and spherical morphology with a tendency to form aggregates were evidenced by TEM images. Optical absorption measurements reveal that the band gap of ZnO decreased from 3.19 to 2.99 eV, which confirmed the existence of Zn-O-Mn interaction. The incorporation of the Mn ions into the ZnO lattice has been studied by EPR spectroscopy and also, the generation of reactive oxygen species (ROS) has been evidenced by using the EPR coupled with the spin trapping probe technique. Here, we report that in addition to altering the crystallite size, morphology and optical absorption characteristics of ZnO, the introduction of Mn dopant also improves the antibacterial efficiency against pathogenic microorganisms, namely Escherichia coli and Bacillus cereus.
关键词： Mn doping,antibacterial activity,ZnO nanoparticles,reactive oxygen species,wet-chemical synthesis
更新于2025-09-04 15:30:14