利用胶体碳球为模板制备SiO2、TiO2、SnO2空心球

介观尺度的氧化物空心球材料在许多领域都有着潜在的应用价值[1],因此近年来受到人们的广泛关注。其制备方法包括:模板法[2],声化学法[3],水热法[4]等。其中胶体粒子模板合成是制备氧化物空心球材料的一条最为有效的途径。常见的胶体粒子有金、银、CdS的纳米粒子,介观尺度的SiO     

Preparation of novel porous carbon spheres from corn starch

Irregular porous carbon spheres were successfully prepared from Na₂SnO₃ coated corn porous starch by carbonization. The product was characterized with X-ray diffraction and scanning electron microscope (SEM). It is verified that the irregular porous carbon spheres are composed of disordered carbon, and the skeleton and pores of the corn porous starch was well preserved after carbonization. The pore size of the irregular porous carbon spheres is almost the same, which is similar to that of the porous starch. And the pore size decreases from about 0.91 μm to 0.53 μm measured from the SEM pictures. The texture of the irregular porous carbon spheres is mainly determined by that of porous starch.     

Facile synthesis of blue-emitting carbon dots@mesoporous silica composite spheres

This paper reported a facile and effective approach towards high-efficient composite luminophores by embedding blue-emitting N-doped carbon dots into spherical SiO₂ matrix (CDs@SiO₂). Mesoporous silica microspheres (r-CDs@MSN) with strong luminescence were synthesized by removing CTAB templates in CDs@SiO₂ using reflux with acetone. The r-CDs@MSN possess a spherical morphology with smooth surface and a diameter of 130 nm, while it exhibits an excitation-independent blue emission peak at 440 nm with an internal quantum yield of 21.5%. BET result shows that the corresponding surface area and adsorption total pore volume are 156.27 m²/g and 0.682 cm³/g, which is suitable for the drugs loading and release. The results indicate that r-CDs@MSN might act as a potential fluorescent drug carrier.     

Novel magnetic SPE method based on carbon nanotubes filled with cobalt ferrite for the analysis of organochlorine pesticides in honey and tea

A novel magnetic SPE method based on magnetic cobalt ferrite filled carbon nanotubes (MFCNTs) coupled with GC with electron capture detection was developed to determine organochlorine pesticides (OCPs) in tea and honey samples. The MFCNTs were prepared through the capillarity of carbon nanotubes for drawing mixed cobalt and iron nitrates solution into their inner cavity followed by heating to 550°C under Ar to form the cobalt ferrite nanoparticles. SEM images provided visible evidence of the filled cobalt ferrite nanoparticles in the multiwalled nanotubes. X‐ray photoelectron spectroscopy indicated no adhesion of cobalt ferrite nanoparticles and metal salts on the outer surface of the MFCNTs. Eight OCPs were extracted with the MFCNTs. The enrichment factors were in the range of 52–68 for eight OCPs. The LODs for the eight OCPs were in the range of 1.3–3.6 ng/L. The recoveries of the OCPs for honey and tea samples were 83.2–128.7 and 72.6–111.0%, respectively. The RSDs for these samples were below 6.8%. The new method is particularly suited to extract nonpolar and weakly polar analytes from a complex matrix and could potentially be extended to other target analytes.     

Reduction in smoke emitted and fire hazard presented by flexible poly (vinyl chloride) through novel synthesis of SnO2 supported by activated carbon spheres

A novel catalyst consisting of SnO₂ supported by activated carbon spheres (ACS), referred to as “ACS@SnO₂,” was demonstrated as being much more efficient than either ACS or SnO₂ alone. As such, it is capable of improving the thermal stability and flame retardancy of flexible poly (vinyl chloride) (fPVC). The resulting ACS@SnO₂ composite exhibits a higher reactivity and excellent stability due to the presence of evenly dispersed SnO₂ particles attached to the ACS, as well as the high degree of graphitization of the ACS. Smoke suppression and the synergistic flame‐retardant effect of the ACS@SnO₂ on the fPVC were thoroughly investigated by performing a cone calorimeter test and thermogravimetric analysis. The cone calorimeter test data reveal that the addition of the ACS@SnO₂ greatly improved the flame retardancy of the fPVC, with 32% and 58.4% decreases in the peak heat release rate and smoke production rate, respectively. This is attributed to the formation of a continuous and compact protective layer and the synergistic effects of the ACS and SnO₂ in promoting the ability of the fPVC to isolate heat and oxygen. Furthermore, the ACS@SnO₂/fPVC composite produced greatly increased amounts of char residue, thereby attenuating the fire hazard presented by fPVC composites.     

Thermal decomposition and cobalt species transformation of carbon nanotubes supported cobalt catalyst for Fischer-Tropsch synthesis

The effect of calcination condition on the cobalt species and Fischer-Tropsch synthesis (FTS) was studied. It was found that higher calcination temperature resulted in decreased FTS activities because CNTs were consumed by oxidation in air at temperature higher than 230°C. Cobalt species went through transformation from Co3O4 to metallic Co in Ar by autoreduction at temperature over 500°C. The autoreduction route might be Co3O4→CoO→Co or Co3O4→Co2C→Co. Reduction at temperature higher than 500°C also resulted in decreased FTS activities due to the methanation of CNTs in hydrogen.     

In-situ deposition of Pd/Pd_4S heterostructure on hollow carbon spheres as efficient electrocatalysts for rechargeable Li-O_2 batteries

The sluggish kinetics of oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) have always restricted the development of lithium oxygen batteries(LOBs).Herein,hollow carbon spheres loaded with Pd/Pd_4S heterostructure(Pd/Pd_4S@HCS) were successfully prepared via the in-situ deposition to improve the electrocatalytic activities for both ORR and OER in LOBs.With the welldispersed Pd/Pd_4S nanoparticles,the hierarchical composite with large specific surface area offers favorable transport channels for ions,electron and oxygen.Especially,the Pd/Pd_4S nanoparticles could exhibit excellent electrochemical performance for ORR and OER due to their intrinsic catalytic property and interfacial effect from the heterostructure.Therefore,the LOBs with Pd/Pd_4S@HCS as cathode catalyst show improved specific capacities,good rate ability and stable cycling performance.     

Copper-mediated synthesis of PdI_2 colloidal spheres

A novel copper-mediated solvothermal method was proposed for synthesizing colloidal spheres of a new composition,palladium iodide(PdI2).Typical procedure was designed to involve the introduction of cupric chloride(CuCl2) as weak oxidant.CuCl2 was found to be essential for preventing the easy formation of palladium deposits as well as facilitating the synthesis and assembly.Under the co-effect of CuCl2 and the surfactant of polyvinylpyrrolidone(PVP),neutral PdI2 colloidal spheres with narrow size distributio...     

Facile polyol synthesis of ultrasmall water-soluble cobalt ferrite nanoparticles

A facile protocol to prepare ultrasmall citrate-coated cobalt ferrite NPs was proposed from the comparison between one-step and two-step chemical routes based on the polyol method. Infrared spectroscopy, thermogravimetry and zeta potential data indicated different coordinations of citrate groups affecting the NP colloidal stability. The magnetic core size and saturation magnetization were also affected. The surface-modified NPs prepared by the one-step route presented superior colloidal stability, low core (2.9 nm) and hydrodynamic (4.8 nm) sizes, high magnetization (45 emu/g), and can be considered suitable platforms to produce nanoparticle-biomolecule conjugates.     

Preparation of multi-walled carbon nanotubes functionalized magnetic particles by sol-gel technology and its application in extraction of estrogens

Magnetic silica particles coated with hydroxy-terminated multi-walled carbon nanotubes (MWCNTs-OH) were prepared by sol-gel technology, characterized and used for the convenient, rapid and efficient extraction of several estrogens (including diethylstilbestrol, estrone and estriol) in water followed by sweeping micellar electrokinetic chromatography analysis with UV detection. The results demonstrated that sol-gel technology was a feasible, simple and effective technique for the preparation of MWCNTs-OH functionalized magnetic silica particles. The factors affecting the extraction efficiency of estrogens (the pre-activation of magnetic particles, adsorption time, desorption time and the amount of elution solvent) were carefully investigated. The extraction efficiencies for diethylstilbestrol, estrone and estriol were 95.9%, 93.9%, and 52.4%, respectively, under the optimum conditions. The method detection limits for the three estrogens were less than 0.2 ng mL⁻¹. The developed method was applied for the analysis of tap water, mineral water, Pearl River water and honey.     

用于高性能钠离子电容器的高氮掺杂多孔碳纳米纤维的简易合成

选择合适的生物质材料是获得功能碳材料的有效途径之一。通过柠檬酸钾和三聚氰胺一步热解法制备高氮掺杂多孔碳纳米纤维(NPCF)。在电流密度为0.1和1.0 A·g^-1时,NPCF电极的容量分别为218和140 mAh·g^-1。同时,具有NPCF阳极的钠离子电容器(SIC)在1.0 A·g^-1下表现出优异的倍率性能和超长的使用寿命,可循环超过2 500次。     

Application of cobalt phthalocyanine as a nanostructured catalyst in the synthesis of biological henna‐based compounds

The present investigation describes synthesis of a good range of henna‐based compounds in the presence of novel nano cobalt phthalocyanine like molten salt (tetra‐2,3‐pyridiniumporphyrazinato cobalt tribromomethanide) [Co (TPPABr)]CBr₃ as an efficient, recyclable and thermally stable heterogeneous catalyst.     

用于高性能钠离子电容器的高氮掺杂多孔碳纳米纤维的简易合成

选择合适的生物质材料是获得功能碳材料的有效途径之一。通过柠檬酸钾和三聚氰胺一步热解法制备高氮掺杂多孔碳纳米纤维(NPCF)。在电流密度为0.1和1.0 A·g^-1时,NPCF电极的容量分别为218和140 mAh·g^-1。同时,具有NPCF阳极的钠离子电容器(SIC)在1.0 A·g^-1下表现出优异的倍率性能和超长的使用寿命,可循环超过2 500次。     

用于高性能钠离子电容器的高氮掺杂多孔碳纳米纤维的简易合成

选择合适的生物质材料是获得功能碳材料的有效途径之一。通过柠檬酸钾和三聚氰胺一步热解法制备了高氮掺杂多孔碳纳米纤维(NPCF)。在电流密度为0.1和1.0 A·g^-1时,NPCF电极的容量分别为218和140 mAh·g^-1。同时,具有NPCF阳极的钠离子电容器(SIC)在1.0 A·g^-1下表现出优异的倍率性能和超长的使用寿命,可循环超过2 500次。     

Synthesis and characterization of multiwall carbon nanotubes/alumina nanohybrid-supported cobalt catalyst in Fischer-Tropsch synthesis

Multiwall carbon nanotubes (MWNTs) and alumina are combined to give a new type of nanohybrid for Fisher-Tropsch synthesis (FTS) catalyst support. Alumina nano-particles (10 wt%) were introduced directly on functionalized MWNTs by a modified sol-gel method. Microstructure observations show that alumina particles were homogeneously dispersed on the inside and outside of modified MWNTs surfaces. 15 wt% cobalt loading catalysts were prepared with this nanohybrid and γ-alumina as a reference, using a sol-gel technique and wet impregnation method respectively. These catalysts were characterized by TEM, XRD, N₂-adsorption, H₂ chemisorption and TPR. The deposition of cobalt nanoparticles synthesized by sol-gel technique on the MWNTs nanohybrid shift the reduction peaks to a low temperature, indicating higher reducibility for uniform cobalt particles. Nanohybrid also aided in high dispersion of metal clusters and high stability and performance of catalyst. The proposed MWNTs nanohybrid-supported cobalt catalysts showed the improved FTS rate (g_HC/(g_cat·min)), CO conversion (%), and water gas shift rate (WGS)(g_CO2/(g_cat·h)) of 0.012, 52, and 30E-3, respectively, as compared to those of 0.007, 25, and 18E-3, respectively, on the γ-alumina-supported cobalt catalysts with the same Co loading.     

One-pot electrochemical synthesis of functionalized fluorescent carbon dots and their selective sensing for mercury ion

We propose a simple, economical, and one-pot method to synthesize water-soluble functionalized fluorescent carbon dots (C-Dots) through electrochemical carbonization of sodium citrate and urea. The as-prepared C-Dots have good photostability and exhibit a high quantum yield of 11.9%. The sizes of the C-Dots are mainly distributed in the range of 1.0–3.5 nm with an average size of 2.4 nm. It has been further used as a novel label-free sensing probe for selective detection of Hg²⁺ ions with detection limit as low as 3.3 nM. The detection linear range is 0.01–10 μM. The as-prepared C-Dots are also successfully applied for the determination of Hg²⁺ in real water samples.     

Impact of solvents and surfactants on the self-assembly of nanostructured amine functionalized silica spheres for CO_2 capture

Macroscopic SiO_2 spheres with a homogeneous amine distribution were synthesized by a one-step emulsion based synthesis approach in a flow column reactor. The CO_2 adsorption capacity of the nanostructured amine-functionalized silica spheres was studied in absence and presence of H_2O. The structural properties were adjusted by varying solvents and surfactants during the synthesis and, at constant amine loadings, were found to be the main factor for influencing the CO_2 sorption capacities. Under water-free conditions CO_2 is bound to the amino groups via the formation of carbamates, which require two neighboring amino groups to adsorb one CO_2 molecule. At constant amine concentrations sorbents with lower surface area allow to establish a higher amine density on the surface, which enhances the CO_2 uptake capacities under dry conditions. In presence of H_2O the CO_2 adsorption changes to 1:1 stoichiometry due to stabilization of carbamates by protonation of H_2O and formation of further species such as bicarbonates, which should in principle double the adsorption capacities. Low concentrations of physisorbed H2O(0.3 mmol/g) did not impair the adsorption capacity of the adsorbents for CO_2, while at higher water uptakes(0.6 and 1.1 mmol/g) the CO_2 uptake is reduced, which could be attributed to capillary condensation of H_2O or formation of bulky reaction products blocking inner pores and access to active sites.