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Photocatalytic oxidation of aromatic alcohols over silver supported on cobalt oxide nanostructured catalyst
摘要： In this paper, we report an in-situ synthesis of silver supported on cobalt oxide (Ag/Co3O4) nanoparticles (NPs) and studied the catalytic activity of this material as an eco-friendly, simple, recyclable and efficient catalyst for one‐pot photocatalytic oxidation of aromatic alcohols. Ag nanoparticles with the sizes of 2–5 nm supported on spherical Co3O4 with the radius between 40 and 60 nm were synthesized by homogeneous chemical precipitation followed by hydrothermal heating. The as-synthesized catalyst was thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), elemental mapping, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and N2 adsorption-desorption isotherm (BET) analysis. It was observed that the catalysts with 1 wt% of silver loading shows high activity and selectivity toward the target aldehyde product. The effects of different reaction parameters such as reaction time, oxidant and solvent were investigated and studied in detail. The synergistic effect between the surface Ag NPs and Co3O4 nanospheres plays a vital role toward very high catalytic activity.
关键词： Oxide materials,Chemical synthesis,Catalysis,X-ray diffraction
更新于2025-09-23 15:23:52
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Single-Step Synthesis and Optical Properties of Bimetallic Fe–Ag Nanoparticles
摘要： Bimetallic nanoparticles containing ferromagnetic iron (Fe) and plasmonic silver (Ag) are synthesized by one-step chemical reduction process. Structural and optical properties of nanoparticles are studied by transmission electron microscopy, X-ray diffraction technique, UV-Visible spectroscopy and photoluminescence measurement. Tunable optical properties with the variation of Ag percentage in the Fe–Ag nanoparticles are observed. Sharp absorption peak due to localized surface plasmon resonance (LSPR) is observed in the visible spectrum range for Fe–Ag nanoparticles which is absent in Fe nanoparticles. LSPR peak shows redshift due to variation in shape and size of the nanoparticles having higher Ag content. Enhanced photoluminescence in the bimetallic nanoparticles is attributed to the observed surface plasmon resonance.
关键词： Optical Properties,Nanostructured Materials,Luminescence,Chemical Synthesis
更新于2025-09-23 15:22:29
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Comparative study on blue-turquoise silicate apatite phosphors prepared via different synthesis routes
摘要： Different types of gel precursors were obtained via microwave-assisted precipitation, gel-combustion, sol–gel, and Pechini methods in order to prepare Ca2Y7.76Ce0.12Tb0.12(SiO4)6O2 phosphors with apatite structure. The processes involved during the thermal treatment of precursors were revealed by TGA– FT-IR coupling. ICP-OES reveals that the incorporation degree of dopants (Ce3+, Tb3+) in silicate lattice are close to theoretical values while Ca2+ and Y3+ values shows differences depending on the synthesis route. The phosphors composition, morphology, structure, and optical characteristics are revealed by SEM, XRD, FTIR, and luminescent investigations. Pure hexagonal apatite with crystallite size of 76.5 nm was identi?ed in sample prepared by gel-combustion, while cubic-Y2O3 and monoclinic-Y2SiO5, as secondary phases, were found in precipitated samples. The purity phase was enhanced by increasing the TEOS amount during precipitation. As a result of the Ce3+ incorporation into different symmetry sites, the excitation spectra are dominated either by 321 or 360 nm band. Turquoise emission of apatites is shifted toward blue region by increasing the excitation wavelength from 231 to 360 nm.
关键词： Silicate apatite,Luminescence,Wet chemical synthesis,Phosphors
更新于2025-09-23 15:22:29
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Sm3+, Tb3+ co-doped NaLa(MoO4)2 temperature sensing materials based on the fluorescence intensity ratio
摘要： In optical temperature sensors, the method of measuring temperature based on Fluorescence Intensity Ratio (FIR) has been paid tremendous attention due to its fortissimo anti-excitation power noise and the ability of anti-signal transmission channel to transmit light unsteady [1e10]. The above method has the advantages of non-contact, resistance to high temperature, wide temperature range, quick response and being able to measure small objects. The optical temperature sensing technology based on the FIR is used to detect the temperature through detecting the ratio of emitted fluorescence intensity between a pair of specific thermal coupling energy levels related to the temperature [11e15]. The fluorescence emission efficiency of Sm3+ doped oxide in 4G5/2 energy level was quite high. Sm3+ emits bright orange-red color. Tb3+ doped oxide is the strongest fluorescence branch in emission from 5D4- 7F5 [16,17]. If the thermal-quenching trend of luminescence of Sm3+ and Tb3+ is different, the FIR will change with temperature. So FIR can be used to indicate the temperature. Therefore, intensive study of Sm3+ and Tb3+ co-doped materials has great prospects, because it can reveal broad luminescence color variability from green to red. Molybdate has chemical stability and thermal stability, rare earth ions have strong 4f-4f transition absorption and transition emission in this host. Therefore it is a wally host [18,19]. Based on the above-mentioned reasons, in this paper Sm3+, Tb3+ co-doped NaLa(MoO4)2 samples of different morphology have been prepared and studies the temperature sensing characteristics.
关键词： Phosphor,Optical temperature sensing,Chemical synthesis,Luminescence
更新于2025-09-23 15:22:29
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Influence of molecular fluorophores on the research field of chemically synthesized carbon dots
摘要： Carbon dots (CDs) – small crystalline or amorphous carbon-based nanoparticles – have attracted much attention as promising fluorescent materials for a wide range of applications. One of their widely accepted advantages is the simplicity of the formation of highly luminescent CDs from a wide variety of organic precursors. At the same time, several recent studies on these chemically synthesized CDs raised questions about the nature of the resulting products. Their strong fluorescence can arise due to the presence of molecular organic fluorophores, not necessary CDs, as was assumed in the earlier publications. In this review, we consider fundamental characteristics of CDs and discuss several issues that currently prevent a better understanding of their structure-property correlation. Analysis of recent related studies identifying the presence of organic fluorophores in CDs with an emphasis on the optical properties of the synthesis products shows that their emission characteristics may be a complex interplay of stand-alone molecular fluorophores and their aggregates, possibly embedded in an amorphous carbon/polymer network. The review concludes with an outlook towards the challenges in the field of the bottom-up synthesized CDs, and their proper identification within the variety of the organic side-products eventually formed during the synthesis.
关键词： Luminescence,Chemical synthesis,Carbon dots,Optical properties,Molecular fluorophores,Aggregation
更新于2025-09-23 15:21:21
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Electrochemical properties of chemically synthesized SnO2-RuO2 mixed films
摘要： The SnO2–RuO2 mixed films are prepared by successive ionic layer adsorption and reaction (SILAR) method. The SnO2 films combined with RuO2 are prepared by varying the deposition cycles of SILAR. The effect of combining SnO2 with RuO2 on structural, morphological and electrochemical properties is studied. It is observed that the crystalline nature of SnO2 changed to amorphous with increase in RuO2 deposition cycles. The morphology is also changed from fibrous-porous to compact after increasing RuO2 deposition cycles. The specific capacitance of SnO2 is increased from 4 to 185 F/g after combined with RuO2. The maximum utilization of RuO2 is observed with specific capacitance of 1010 F/g.
关键词： RuO2,SnO2,Supercapacitor,Thin films,Chemical synthesis,Charge–discharge
更新于2025-09-23 15:21:21
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In-situ pulsed laser induced growth of CdS nanoparticles on ZnO nanorods surfaces
摘要： Herein we present a process for the in-situ growth of CdS nanoparticles using a pulsed laser irradiation. A Nd-YAG laser was applied to ZnO nanorods previously submerged in an aqueous precursor solution containing cadmium chloride and thiourea. For optimum values of the laser fluence, around 40 mJ/cm2 it was possible to fabricate a highly homogeneous film of CdS nanoparticles covering the ZnO nanorods surface. Cathodoluminescence measurements of the ZnO/CdS structure show the quenching of the ZnO yellow and green luminescence, indicating the ZnO surface defects passivation by CdS nanostructures. Although lasers have been already used for inducing growth in solution, this work presents new evidence of in-situ growth on the surface of nanostructured materials. The laser based technique presented is simple, easy to implement, scalable and it could be applied in the fabrication of nanostructured solar cells and other devices.
关键词： A. Inorganic compounds,D. Defects,A. Nanostructures,B. Chemical synthesis,C. Electron microscopy
更新于2025-09-23 15:19:57
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Facile microwave-assisted synthesis of Cr2O3 nanoparticles with high near-infrared reflection for roof-top cooling applications
摘要： Microwave-assisted solution synthesis was employed for the preparation of Cr2O3 nanoparticles using Cr(acac)3 and ethylene glycol. The optimum conditions for the completion of the reaction forming a green precipitate (yield-95%) were: irradiation for 40e60 min at 220 (cid:1)C solution temperature. The as-prepared sample was barely crystalline; annealing in air at above 300 (cid:1)C formed nanocrystalline Cr2O3, as shown by X-ray diffraction (XRD). High-resolution transmission electron microscopy (HRTEM) of the “700 (cid:1)C sample” con?rmed the well-crystallised Cr2O3 formation with ~37 nm average size. The as-prepared powder (bluish-green) showed high near-infrared (NIR) re?ectance, whereas the annealed samples showed bright-green re?ectance, whose International Commission on Illumination L*a*b* (CIE L*a*b*) values shifted towards the green region. The higher Dq/B value (3.76), suggested that Cr3t lies in a strong crystal ?eld. Stainless steel blocks covered with the as-prepared (intermediate) material reduced heating under sunlight by 5 (cid:1)C, indicating its suitability as an easily prepared tile coating for roof-top applications. The annealed samples are found suitable as an anti-dazzling coating for automobile windscreens and rear-view mirrors.
关键词： Chemical synthesis,Ceramics,Microwave-assisted synthesis,Oxide materials,Cr2O3 nanoparticles
更新于2025-09-19 17:15:36
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Facile Synthesis and Characterization of Uniform PbS Nanorods
摘要： This work reports a facile solution route for the synthesis of uniform PbS nanorods in high yield by the reaction of lead acetate trihydrate (Pb(CH3COO)2·3H2O) and thioacetamide (TAA) with the assistance of surfactant cetyltrimethylammonium bromide (CTAB). The morphology, structure and optical properties of the products were characterized by means of X-ray powder diffraction (XRD), energy-dispersive X-ray spectrometry (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis-NIR absorption spectroscopy and photoluminescence (PL) spectroscopy. It was found that the nanorods have a diameter of 36 nm and a length of 110 nm and show good UV-Vis-NIR absorption and PL emission properties. Moreover, a possible growth mechanism of formation PbS nanorods was proposed.
关键词： Chemical Synthesis,Crystal Growth,PbS Nanorods,Nanostructured Materials
更新于2025-09-19 17:15:36
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Novel I-doped Bi12O17Cl2 photocatalysts with enhanced photocatalytic activity for contaminants removal
摘要： Novel I-doped Bi12O17Cl2 photocatalysts have been synthesized using a facile chemical precipitation method and characterized by XRD, XPS, SEM, BET and UV–vis DRS etc. The corresponding results indicate that I- ions enter into the crystal lattices of Bi12O17Cl2 and replace partial Cl- ions form an impurity level over valence band and extend the visible light absorption ranges of Bi12O17Cl2. I-doped Bi12O17Cl2 exhibits much superior visible-light (λ > 420 nm) photocatalytic activity to that of the pure Bi12O17Cl2 in the methyl orange (MO) and phenol degradation, because a little amount of I- ions can boost the photocharges separation efficiency, which is ensured by photoluminescence spectra, transient photocurrent responses and electrochemical impedance spectra. It is expected that this work opens a new potential pathway to improve the photocatalytic activity of non-stoichiometric ratios bismuth oxyhalide via ions doping strategy.
关键词： B. Chemical synthesis,C. Electrochemical measurements,D. Catalytic properties,A. Semiconductors
更新于2025-09-19 17:15:36