Facile synthesis of high surface area molybdenum carbide nanoparticles

Molybdenum carbide has immense potential as an active catalyst for reaction systems such as synthesis of important chemicals like ammonia. However, the carbide is not used as a commercial catalyst or support as the current synthesis processes produce low surface area material or have contaminants such as excess carbon and surface and chemisorbed oxygen. Moreover, attempts to refine the synthesis pathways are usually not supported by any thermochemical modeling. In this study, a facile and reproducible method to synthesize high surface area molybdenum carbide was developed with the help of thermochemical modeling to better understand molybdenum-carbon phase behavior. We have synthesized 2-5 nm particles of Mo_xC with surface areas of up to 360 m²/g as characterized using a variety of techniques including X-ray diffraction and electron microscopy.     

表面活性剂调节高矫顽力FePt纳米颗粒的合成

在表面活性剂聚乙烯吡咯烷酮(PVP)存在的体系中,通过NaBH4还原前驱体Fe(acac)3和H2PtCl6·6H2O,制备出了单分散的尺寸在3.0 nm左右的FePt纳米颗粒。XRD和TEM表征结果显示,表面活性剂PVP的用量影响FePt纳米颗粒相变,但对颗粒的尺寸无明显作用。由此推测,PVP对FePt纳米颗粒的相变起"催化"作用,适量的PVP诱导纳米颗粒的相变,可以通过改变表面活性剂的用量来调节FePt纳米颗粒的磁性能,当表面活性剂PVP单体与FePt前驱体的摩尔比(PVP/FePt)为7时,制得的FePt纳米颗粒经过500℃保温30 min热处理后,矫顽力高达5.2 kOe。     

Facile synthesis of a novel photocatalyst with integrated features for industrial effluents treatment

Faster charge transport, excellent charge separation, narrow bandgap energy, lower electron-hole pair recombination rate, and high visible light absorption are the key features of an ideal photocatalyst material. Undoubtedly, semiconductor-based photocatalysts having remarkable charge separation efficiency have attracted considerable attention for degrading hazardous organic pollutants from contaminated water. So herein, a novel composite of reduced graphene oxide (rGO) supported by gadolinium doped bismuth yttrium oxide (Gd-BiYO₃/rGO) was prepared by simple precipitation and ultrasonication method. The photocatalytic efficiency of the Gd-BiYO₃/rGO composite was examined comparatively with pure BiYO₃ and Gd-BiYO₃ samples to degrade Methylene Blue (MB) dye under visible light irradiation. The Gd doping and rGO incorporation into BiYO₃ increased the conductivity, improved the charge transfer efficiency, and impeded the charge recombination, resulting in superior photocatalytic activity of Gd-BiYO₃/rGO. The kinetic studies exhibited the 96.2%, 61.5%, and 48.3% degradation of MB after 80 min irradiation of 1 SUN visible light under Gd-BiYO₃/rGO, Gd-BiYO₃, and BiYO₃, respectively. The Gd-BiYO₃/rGO composite degraded the MB dye at a rate (k = 0.0328 min^-1) that is 5.05 and 2.68-fold higher than pure BiYO₃ and Gd-BiYO₃, correspondingly. The transient photocurrent response of Gd-BiYO₃/rGO was comparatively 4.7 and 2.8 times greater than that of BiYO₃ and Gd-BiYO₃ photocatalysts, respectively. The dominant photocatalytic performance of Gd-BiYO₃/rGO is primarily ascribed to the formation of heterojunctions between rGO nanosheets and Gd-BiYO_3, which facilitate higher visible light absorbance, effective charge separation, and transfer through interfacial layers, more dye adsorption, lower charge transfer resistance, and hamper electron-hole pair recombination. Overall, the electrochemical results suggest that the current study provides an effective way to synthesize a heterostructure photocatalyst for removing organic pollutants from industrial effluents.     

Facile synthesis of In2O3 nanoparticles with high response to formaldehyde at low temperature

In₂O₃ nanoparticles with uniform particle size (10-25 nm) were obtained using the facile precipitation strategy at room temperature with following calcined treatment. The gas-sensing performance of In₂O₃ nanoparticles with different calcined temperatures was investigated. The results demonstrated that the In₂O₃ nanoparticles calcined at 500°C exhibited highest sensing response (R_a/R_g = 68.1) to 10 ppm HCHO at 100°C with good selectivity, stability, reproducibility, and ultra-low limit of detection (1 ppm). The results of XPS, UV, and other characterizations indicated that In₂O₃-500 possessed the most absorbed oxygen species, the highest carrier mobility, and lowest band gap energies. Our work offers new insights into the development of sensing materials to the detection of volatile organic compounds (VOCs).     

Facile synthesis of monodispersed silica-coated magnetic nanoparticles

Silica-coated magnetic nanoparticles (MNPs) have great potential for use in field of biotechnology owing to their unique properties, which can be manipulated by an external magnetic field gradient. Herein, we describe a method for facile synthesis of monodispersed silica-coated MNPs (MNP@SiO₂ NPs). Commercially available oleate-MNPs were successfully converted to polyvinylpyrrolidone-MNPs (PVP-MNPs), and then coated with silica by the modified Stöber method. More than 95% of MNPs were individually coated with a silica shell; non-magnetic core silica nanoparticles (NPs) were not detected. Notably, the MNP@SiO₂ NPs are highly monodispersed in size (size distribution < 2.5%) and synthesis at the scale of grams was easily obtained by a simple scale up process. Moreover, aggregation was not detected upon storage of over three months.     

高压固相法合成CdS纳米粒子及其表征

以固相合成法在不同的压力条件下利用温度控制,快速合成CdS纳米粒子.通过X射线粉末衍射、透射电镜和荧光光度计,对CdS纳米粒子的结构及光学性质进行了表征.利用XRD研究了同一添加剂下不同反应温度、不同压力对蚋米粒子足寸的影响,利用TEM表征了产物的形貌.结果表明,在添加剂丙三醇存在条件下,控制反应温度和压力对粒径均有一定的影响.     

Facile synthesis of functionalized porous carbon with three-dimensional interconnected pore structure for high volumetric performance supercapacitors

Functionalized porous carbon with three-dimensional (3D) interconnected pore structure has been successfully synthesized through direct heat-treatment of KOH-soaked soybeans. Benefiting from heteroatoms (N, O) doping, interconnected porous carbon framework with high surface area as well as high packing density (up to 1.1 g cm⁻³), the as-obtained porous carbon material exhibits high volumetric capacitance of 468 F cm⁻³, good rate capability and excellent cycling stability (91% of capacitance retention after 10,000 cycles) in 6 M KOH electolyte. More importantly, the as-assembled symmetric supercapacitor delivers high volumetric energy density of 28.6 Wh L⁻¹ in 1 M Na₂SO₄ aqueous solution.     

Facile synthesis of cobalt nanoparticles embedded in a rod-like porous carbon matrix with excellent electromagnetic wave absorption performance

A rod-like porous Co/C composite was successfully fabricated by carbonizing a Co-based MOF-74 precursor. Due to significant synergy between the porous carbon framework (dielectric loss) and cobalt nanoparticles (magnetic loss) coupled with the multiple polarization loss (interfacial or dipole polarization loss) due to the porous nature of the structure, the Co/C composites showed extremely favorable microwave absorption performance. When the as-prepared cobalt-based MOF precursor was annealed at 700 °C (S700), the supreme EM wave reflection performance was ?38.46 dB at 7.82 GHz with a coating thickness of 2.5 mm, whereas the broadest effective absorption bandwidth (3.3 GHz) was obtained with a coating thickness of 1.5 mm. Moreover, S600 samples exhibited an expansive absorption bandwidth range of 14.82 GHz (3.18–18 GHz) as the coating thickness was varied from 1.0 mm to 5.5 mm. The unique rod-like porous Co/C samples prepared in this study have significant potential for application in the field of the EM wave absorption.     

Facile synthesis of metal nanoparticles using conducting polymer colloids

We report a simple method to synthesize Ag, Au, and Pt nanoparticles with a reasonable size dispersity using water-dispersible conducting polymer colloids composed of polyaniline (PANI) and conventional polyelectrolyte. This facile synthesis results in single crystalline metal nanoparticles that are stable in an aqueous solution for at least several weeks. The process involves incrementally adding a metal ion solution to aqueous conducting polymer colloids and does not require reducing agents such as NaBH₄. In addition, the complete synthetic and purification procedure is carried out in an aqueous solution; therefore, it is environmentally benign and potentially suitable for large-scale production. We have also demonstrated synthesis of larger nanoparticles and nanosheets by varying the experimental parameters. With the tunable oxidation states of conducting polymers, we expect this synthetic platform can synthesize a wide range of nanostructured metals with specific size, shape and properties. Finally, the nanoparticles embedded in the conducting polymer matrix, the metal-polyaniline nanocomposite itself may be interesting since it represents a type of materials where metallic nanoislands are embedded in a semiconducting matrix.     

Facile synthesis of nanocrystalline magnesium oxide with high surface area

Nanocrystalline magnesium oxide with high surface area has been synthesized by precipitation method using ammonium hydroxide and polyvinyl alcohol as precipitant and polymeric surfactant, respectively. The results show that the polymeric surfactant (PVA) has a significant effect on the synthesis of MgO nanocrystals. The specific surface area of the MgO powder decreases from 123 m²g^− 1 to 61 m²g^− 1and the crystallite size on the (200) plane increases from 12.2 nm to 14.2 nm with increasing temperature from 600 °C to 800 °C. Transmission electron microscopy (TEM) and N₂ adsorption/desorption isotherm also show a nanostructure consisting of aggregates or agglomerates of particles forming slit shaped pores (plates or edged particles like cubes).     

Facile synthesis of novel zinc-based infinite coordination polymer nanoparticles

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Facile synthesis of monodisperse ZnS capped CdS nanocrystals exhibiting efficient blue emission

A new method for the capping of colloidal CdS nanocrystals with ZnS shells is presented. A combination of the monomolecular precursor zinc ethylxanthate (Zn(ex)₂) and zinc stearate was used to replace hazardous organometallic reagents usually applied in this procedure, i.e. bis(trimethylsilyl) sulfide and diethylzinc. Its simple preparation, air-stability and low decomposition temperature of 150 °C make Zn(ex)₂ a very suitable source for the ZnS shell growth. With this precursor, highly luminescent CdS/ZnS core/shell nanocrystals (Q.Y. 35–45%), exhibiting narrow emission linewidths of 15–18 nm (FWHM) in the blue spectral region, can reproducibly be obtained.     

Facile synthesis of graphitic carbons decorated with SnO2 nanoparticles and their application as high capacity lithium-ion battery anodes

A facile and potentially scalable synthesis route to obtain SnO₂–carbon composites was developed. SnO₂ nanoparticles were deposited on the surface of two types of graphitic carbon: (a) commercial porous graphite (HG) and (b) graphitic carbon nanostructures. The synthesis procedure consists of two simple steps: (i) room temperature formation/deposition of SnO₂ nanocrystals and (ii) thermal treatment at 350 °C to generate SnO₂ nanoparticles (size ~3.5 nm) over the carbon surface. The electrochemical performance of the graphitic carbons and the SnO₂–carbon composites as anode materials in Li-ion rechargeable batteries was investigated. In all cases, tape casting electrode fabrication allowed almost full active material utilization. Good cyclabilities were achieved, with HG and HG–SnO₂ showing capacities of 356 and 545 mAh g⁻¹, respectively after 50 cycles.     

Facile solvothermal synthesis of cube-like Ag@AgCl: a highly efficient visible light photocatalyst

In this paper, a stable and highly efficient plasmonic photocatalyst, Ag@AgCl, with cube-like morphology, has been successfully prepared via a simple hydrothermal method. Using methylene dichloride as chlorine source in the synthesis can efficiently control the morphology of Ag@AgCl, due to the low release rate of chloride ions. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra were used to characterize the obtained product. The photocatalytic activity of the obtained product was evaluated by the photodegradation of methyl orange (MO) under visible light irradiation, and it was found, interestingly, that Ag@AgCl exhibits high visible light photocatalytic activity and good stability.     

Facile synthesis of Y-doped graphitic carbon nitride with enhanced photocatalytic performance

Yttrium-doped graphitic carbon nitride (Y/g-C₃N₄) catalysts were prepared via a facile pyrolysis method with urea used as a precursor and yttrium nitrate as the Y source. Characterization results show that an appropriate doping ratio of Y can be embedded into in-planes of g-C₃N₄. The Y/g-C₃N₄ catalysts are characterized by hierarchical porosity, large specific surface area, and large pore volume. Introduction of Y species effectively extends the spectral response of g-C₃N₄ from ultraviolet to visible region and decelerates the recombination of photogenerated electrons and holes. Because of these properties, the Y/g-C₃N₄ catalysts show an enhanced photocatalytic performance in rhodamine B degradation under visible light.     

Facile construction of C3N4-TE@TiO2/UiO-66 with double Z-scheme structure as high performance photocatalyst for degradation of tetracycline

In the current research, a double Z-scheme photocatalyst C₃N₄-TE@TiO₂/UiO-66 (CNTU) is fabricated via a two-steps facile solvothermal method from Z-scheme C₃N₄-TE@TiO₂ (CNT). This double Z-scheme photocatalyst reveals greater performance for the removal of tetracycline (TC) than pristine C₃N₄-TE, TiO₂, UiO-66 (U66), and their binary compounds. The optimized composite 35C₃N₄-TE@TiO₂/35UiO-66 (35CNTU), exhibitions photocatalytic performance for antibiotic removal (TC) more than 5,4 and 2 times higher than that pure TiO₂, UiO-66, and C₃N₄-TE, respectively. The physical and chemical features of synthesized samples were described via FTIR, XRD, SEM-EDX, TEM, BET, UV–Vis DRS, and PL. The key parameters on photocatalytic performances of 35CNTU such as pH, the amount of catalyst, and the primary concentration of TC were clari?ed. The advancement of the photocatalytic process for 35CNTU is due to the increase in the surface area and structure of double Z-scheme in this compound, which growths the active sites of the reaction as well as better separation of the photo-induced electron and hole pairs. Furthermore, 35CNTU can be recycled with superior stability for 5 cycles. The photocatalytic removal proficiency of TC over 35CNTU under visible light achieves 96% in 40 min. The findings of this study could inspire various novel plans for fabricating practical double Z-scheme photocatalyst for great performance and extensive useful applications.     

Facile synthesis and optical properties of polymer-laced ZnO-Au hybrid nanoparticles

Bi-phase dispersible ZnO-Au hybrid nanoparticles were synthesized via one-pot non-aqueous nanoemulsion using the triblock copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) as the surfactant. The characterization shows that the polymer-laced ZnO-Au nanoparticles are monosized and of high crystallinity and demonstrate excellent dispersibility and optical performance in both organic and aqueous medium, revealing the effects of quantum confinement and medium. The findings show two well-behaved absorption bands locating at approximately 360 nm from ZnO and between 520 and 550 nm from the surface plasmon resonance of the nanosized Au and multiple visible fingerprint photoluminescent emissions. Consequently, the wide optical absorbance and fluorescent activity in different solvents could be promising for biosensing, photocatalysis, photodegradation, and optoelectronic devices.     

Facile synthesis of nitrogen and oxygen co-doped hierarchical porous carbon materials for high performance super capacitors

Journal of Porous Materials - Nitrogen and oxygen co-doped hierarchical porous carbons (NOPCs) is prepared by the pyrolysis of polyethylene glycol-200 (PEG) and triazine carbon forming agent (CFA)...