- 标题
- 摘要
- 关键词
- 实验方案
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Surface structural alteration of multi-walled carbon nanotubes decorated by nickel nanoparticles based on laser ablation/chemical reduction methods to enhance hydrogen storage properties
摘要： The catalytic effect of nickel is addressed to decorate the multi-walled carbon nanotubes for the purpose of hydrogen storage. The hydrogen sorption/desorption are investigated using the volumetric technique. Nickel nanoparticles are distributed on the surface of nanotubes using the laser ablation/chemical reduction treatments. The hydrogen uptake is elevated at higher nickel population up to a certain value and then experiences a significant drop for larger nickel content. The laser treatment is accompanied by the induced pores around nanotubes. This gives rise to the creation of the larger pores at higher laser doses leading to decrease the hydrogen trapping. Despite the pore size distribution strongly alters during both synthesis methods, however the abundance of small pore size in laser treatments is relatively higher than the that of the other technique. In comparison, the laser ablation demonstrates a relatively smaller desorption temperature against chemical one, mainly owing to the formation of larger pore size/volume. Generally, the hydrogen trapping efficiently takes place in the laser treated samples against chemical reduction method. The highest value of hydrogen storage ~1% (0.6% weight) is corresponding to 12.3% (13% weight) of nickel loading via the laser ablation (chemical reduction).
关键词： Hydrogen uptake,Nickel nanoparticles,Laser ablation,Chemical reduction,Pore size
更新于2025-09-23 15:22:29
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Peripherally functionalized based dendrimers as the template for synthesis of silver nanoparticles and investigation the affecting factors on their properties
摘要： Today, dendrimers (D) were introduced as a versatile template for the synthesis of nanoparticles (NPs). In this work, the stable silver nanoparticles (AgNPs) is successfully synthesized through the chemical reduction of AgNO3 using NaBH4 as a reducing agent. Synthesis of AgNPs was performed in the presence of different generations of citric acid-based dendrimers (G1, G2 and G3) and hydroxyl-terminated citric acid-based dendrimers (G1-OH, G2-OH and G3-OH). High-resolution transmission electron microscopy, electron diffraction and energy-dispersive X-ray analysis were used to characterize the synthesized AgNPs. UV–Vis results were used for the qualitative study of the synthesized AgNPs properties. With varying the molar ratio of dendrimer/Ag+, generations of dendrimers and the pH of the solution, the size and size distribution of AgNPs could be easily controlled at room temperature. The average diameter of the synthesized AgNPs in the presence of Gn-OH was in the range of 8–20 nm. Results show that G1-OH alkaline medium with 1:1 molar ratio of D/Ag is the optimum condition for the synthesis of AgNPs. All the obtained results from this study showed that controlling the medium conditions allows AgNPs with the desired size to be obtained.
关键词： Chemical reduction,Silver nanoparticles,Citric acid,Hydroxyl-terminated dendrimer,Dendrimer
更新于2025-09-23 15:21:01
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A Schottky-junction-based platinum nanoclusters@silicon carbide nanosheet as long-term stable hydrogen sensors
摘要： Hydrogen gas sensors which could be applied in harsh environments (high temperature, corrosion atmosphere, etc.) are highly demanded in special fields such as aerospace and chemical industry. Here, we have successfully produced a platinum nanoclusters@silicon carbide nanosheets (Pt NCs@SiC NSs) gas sensor via a simple one-step wet chemical reduction reaction. The Pt NCs@SiC NSs show good response (15.7%) towards 500 ppm hydrogen under 300 °C. Besides, this device possesses a good linear response towards different hydrogen concentration under 500 ppm and keeps a good stability in one month. The gas sensing properties of Pt NCs@SiC NSs are mainly from the Schottky junction-based structure, in which both reception and transduction process play important roles. This work provides a simple way to prepare high-temperature hydrogen sensors without complex equipment, and the large-scale preparation is also available.
关键词： hydrogen sensing,Pt nanoclusters@SiC nanosheets,chemical reduction reaction,high-temperature
更新于2025-09-23 15:19:57
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Synthesis and characterization of size controlled alloy nanoparticles
摘要： Bimetallic and multimetallic alloy nanoparticles are emerging as a class of critical nanomaterials in electronic, optical and magnetic fields due to their unique physic-chemical properties. In particular, precise control of the nanoparticle size can endow them with broad versatility and high selectivity. This chapter reviews some tremendous achievements in the development of size controlled bimetallic and multimetallic alloy nanoparticles, with special emphasis on general preparation methods, characterization methodologies and instrumentation techniques. Some key factors and future perspectives on the development of size-controlled bimetallic and multimetallic alloy nanoparticles are also discussed.
关键词： Thermal decomposition,Bimetallic and multimetallic alloy nanoparticles,Chemical reduction,Electrochemical deposition,Controlled size
更新于2025-09-12 10:27:22
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Pt/TiO2 nanotube photocatalyst – Effect of synthesis methods on valance state of Pt and its influence on hydrogen production and dye degradation
摘要： Direct conversion of solar energy into clean fuels is emerging as an efficient way for the future energy generation and solving environmental issues. Especially, photocatalytic splitting of water into H2 under solar light irradiation is one of the best techniques for clean energy production. Also, decomposition of organic pollutants using solar light is an urgent need to protect the environment. Hence, in the present study, we studied Pt-TiO2 nanotubes based composites for H2 generation and methyl orange dye degradation under solar light irradiation and compared the effect of deposition methods namely photo-deposition and chemical reduction methods. We have achieved the highest rate of H2 generation activity compared to other Pt-TiO2 based composite photocatalysts reported previously, and it is ≈ 173. mmol. h-1.g-1 cat for both photo-deposited and chemically reduced Pt/TiO2 nanotubes. This is about 46.8 folds higher than the pristine TiO2 nanotubes at the same experimental conditions. The selected catalysts were tested for degradation of methyl orange dye, where the catalyst prepared by chemical reduction method showed improved activity (94% degradation in 30 min) compared to the one which is prepared by photo-deposition method (50.5% degradation in 30 min). XPS analysis revealed that the photo-deposited catalyst consist only metallic Pt?, while the chemical-reduction yielded Pt with multiple oxidation states, Pt?, Pt2+ and Pt4+.
关键词： dye degradation,photo-deposition,chemical reduction,Solar energy,hydrogen production,photocatalysis
更新于2025-09-10 09:29:36
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Facile synthesis of Cu2O particles with different morphologies
摘要： Cu2O particles with cubic, octahedral, truncated octahedral and cubic truncated morphologies were synthesized using a simple chemical reduction method at room temperature. The nanocrystals were synthesized directly in aqueous solution by varying the molar concentration of CuCl2 precursor salt added to the sodium borohydride NaBH4 as a reducing agent. The solids obtained were characterized by ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). UV-vis absorption spectra exhibit peaks with characteristic wavelengths of Cu2O. SEM and TEM reveal particles with a cubic morphology at 15 mM CuCl2, with an average particle size of 100 nm. Cu2O particles are also grown in an octahedral shape at 16 mM of CuCl2, having an average particle size of 150 nm. Finally, truncated octahedral and truncated cubic forms were produced for concentrations in the range of 17 to 20 mM with 100 nm of average size.
关键词： Electron microscopy,Chemical-reduction synthesis,Sodium borohydride,Different-shape morphologies,Cooper oxide
更新于2025-09-09 09:28:46