Characterization of Pd/TiO2 embedded in multi-walled carbon nanotube catalyst with a high photocatalytic activity

Pd particles loading on TiO₂-embedded multi-walled carbon nanotubes (MWCNTs), MWCNTs, and TiO₂ particles were prepared via an impregnation method with palladium(II) chlorate solution followed by heat treatment at high temperature. To characterize the catalysts, BET surface area, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy were employed. The prepared catalysts were tested in degradation of methyl orange under visible light. Pd/TiO₂-MWCNTs catalyst demonstrates the highest photocatalytic activity, and the phase transformation from PdO to Pd0 phase takes place at heat treatment of embedded TiO₂. The nanoparticles size of TiO₂ can be decreased by introduction of MWCNTs species. Combining structural characterization with kinetic study results we could conclude that the superior catalytic performance could arise due to the Pd/TiO₂-MWCNTs catalyst’s structure.     

Aminophenol-based carbon dots with dual wavelength fluorescence emission for determination of heparin

We describe the preparation of carbon quantum dots (C-dots) by a one-step hydrothermal method starting from o-aminophenol as the precursor. The C-dots exhibit bright both blue fluorescence (with excitation/emission peaks at 300/410 nm and with quantum yield of 0.40) and green fluorescence (420/500 nm; QY 0.28) without any other element doping. The unique emission properties are attributed to a synergistic effect of amino and hydroxy groups on the surface of the C-dots. The C-dots are shown to be viable fluorescent probes for heparin. The positively charged surface amino groups are assumed to interact with sulfate and carboxy groups in heparin via electrostatic interactions and hydrogen bonding. This causes the blue fluorescence of C-dots to be turned off (quenched). Fluorescence is strongest at a pH value of 6. The fluorometric calibration plot is linear in the 10 to 100 nM concentration range, with an 8.2 nM detection limit (at a signal-to-noise ratio of 3).

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Graphical abstract Carbon quantum dots with dual fluorescence emission bands were synthesized and are shown to be a viable fluorescent probe for heparin.

     

Thermal properties and combustion behaviors of flame retarded epoxy acrylate with a chitosan based flame retardant containing phosphorus and acrylate structure

Functional materials prepared from natural resources arouse a great interest recently. Herein, a novel natural material based flame retardant chitosan phosphate acrylate (GPCS) containing phosphorus and acrylate structure has been prepared. Its effect on thermal properties and combustion behaviors of epoxy acrylate (EA) has been investigated. Microscale combustion calorimeter (MCC) data showed that GPCS reduced the peak heat release (PHRR) and total heat release (THR) of samples greatly, which meant that GPCS was efficient in reducing the flammability of EA. The results of thermogravimetric analysis (TGA) exhibited that GPCS improved the thermal stability of materials at high temperature. Investigation of real time Fourier transform infrared (RT-IR) and thermogravimetric analysis/infrared spectrometry (TGA-IR) revealed that GPCS promoted the formation of char and reduced the release of combustible gas. Thermomechanical properties data showed that the storage modulus of samples increased then decreased with increasing GPCS content while the glass transition temperature continued reduced.     

Porous Molybdenum Phosphide Nano‐Octahedrons Derived from Confined Phosphorization in UIO‐66 for Efficient Hydrogen Evolution

Herein, a series of porous nano‐structured carbocatalysts have been fused and decorated by Mo‐based composites, such as Mo₂C, MoN, and MoP, to form a hybrid structures. Using the open porosity derived from the pyrolysis of metal–organic frameworks (MOFs), the highly dispersive MoO₂ small nanoparticles can be deposited in porous carbon by chemical vapor deposition (CVD). Undergoing different treatments of carbonization, nitridation, and phosphorization, the Mo₂C‐, MoN‐, and MoP‐decorated carbocatalysts can be selectively prepared with un‐changed morphology. Among these Mo‐based composites, the MoP@Porous carbon (MoP@PC) composites exhibited remarkable catalytic activity for the hydrogen evolution reaction (HER) in 0.5 m H₂SO₄ aqueous solution versus MoO₂@PC, Mo₂C@PC, and MoN@PC. This study gives a promising family of multifunctional lab‐on‐a‐particle architectures which shed light on energy conversion and fuel‐cell catalysis.     

Inclusion Complex of β-cyclodextrin with CTAB in Aqueous Solution

Cetyltrimethylammonium bromide (CTAB)/potassium bromide (KBr) micellar system has been used as a viscosity probe to study the inclusion complexation between β-cyclodextrin (β-CD) and CTAB. Viscosity measurements show that the inclusion complexation between β-CD and CTAB may cause the breakdown of CTAB/KBr wormlike micelles, resulting in the decrease of the solution viscosity. The viscosity minimum at C_β-CD/C_CTAB=2 indicate the molecular ratio of host molecule to guest molecule is 2:1 in the β-CD/CTAB inclusion complex.     

铁酸锰/腐植酸复合材料制备及其对亚甲基蓝吸附性能

采用化学共沉淀法合成了一种腐植酸(Humic Acid,HA)包覆铁酸锰型磁性复合材料(MnFe₂O₄/HA)。采用扫描电子显微镜(SEM)、粉末X射线衍射(XRD)和傅里叶变换红外光谱(FT-IR)等技术手段对其进行表征和分析表明,合成产物颗粒大小约200 nm,具有典型的尖晶石结构,腐植酸成功包覆在MnFe₂O₄颗粒表面,饱和磁化强度为34.01 A·m²/kg,在外界低磁场作用下30 s内便可从水溶液分离。 MnFe₂O₄/HA对亚甲基蓝的吸附是一个准二级动力学过程,在2 h达到平衡,较好的符合Langmuir吸附模型。 与MnFe₂O₄相比其对亚甲基蓝的吸附能力显著增强,室温下pH=9时最大吸附量可以达到29.94 mg/g。 MnFe₂O₄/HA可以作为一种有效去除水体中亚甲基蓝污染物的吸附材料。     

Hollow Zn/Co ZIF Particles Derived from Core–Shell ZIF‐67@ZIF‐8 as Selective Catalyst for the Semi‐Hydrogenation of Acetylene

The rational design of metal–organic frameworks (MOFs) with hollow features and tunable porosity at the nanoscale can enhance their intrinsic properties and stimulates increasing attentions. In this Communication, we demonstrate that methanol can affect the coordination mode of ZIF‐67 in the presence of Co²⁺ and induces a mild phase transformation under solvothermal conditions. By applying this transformation process to the ZIF‐67@ZIF‐8 core–shell structures, a well‐defined hollow Zn/Co ZIF rhombic dodecahedron can be obtained. The manufacturing of hollow MOFs enables us to prepare a noble metal@MOF yolk‐shell composite with controlled spatial distribution and morphology. The enhanced gas storage and porous confinement that originate from the hollow interior and coating of ZIF‐8 confers this unique catalyst with superior activity and selectivity toward the semi‐hydrogenation of acetylene.     

Enhanced electrochemiluminescence based on Ru(bpy)32+-doped silica nanoparticles and graphene composite for analysis of melamine in milk

A sensitive electrochemiluminescence (ECL) sensor for melamine analysis was fabricated based on Ru(bpy)₃²⁺-doped silica (Ru(bpy)₃²⁺@SiO₂) nanoparticles and graphene composite. Spherical Ru(bpy)₃²⁺@SiO₂ nanoparticles with uniform size about 55 nm were prepared by the reverse microemulsion method. Since per Ru(bpy)₃²⁺@SiO₂ nanoparticle encapsulated a great deal of Ru(bpy)₃²⁺, the ECL intensity has been greatly enhanced, which resulted in high sensitivity. Due to its extraordinary electric conductivity, graphene improved the conductivity and accelerated the electron transfer rate. In addition, graphene could work as electronic channel improving the efficient luminophor amount participating in the ECL reaction, which further enhanced the ECL signal. This proposed sensor was used to melamine analysis and the ECL intensity was proportional to logarithmic melamine concentration range from 1 × 10⁻¹³ M to 1 × 10⁻⁸ M with the detect limit as low as 1 × 10⁻¹³ M. In application to detect melamine in milk, satisfactory recoveries could be obtained, which indicated this sensor having potential application in melamine analysis in real samples.     

水浴法制备蝴蝶状的微结构CuO

以硝酸铜为铜源,六次甲基四胺为有机碱,去离子水为溶剂,采用简捷水浴加热技术控制合成了由三角纳米片组成的蝴蝶状微结构CuO。产品的组成和形貌用XRD、EDX、场发射扫描电镜(FESEM)、TEM、HRTEM和选区电子衍射(SAED)进行了表征。结果表明CuO的形貌主要受六次甲基四胺用量的影响。随着其用量的增加,CuO的形貌经历了飞鱼状-蝴蝶状-牡丹状的递变。并对蝴蝶状CuO微结构的形成机制及形貌的演变进行了探讨。     

溶剂热合成多级结构的Cu_3SnS_4月季花状微球

以CuCl2·2H2O、SnCl2和硫脲为原料,在乙二醇溶剂热条件下,制得具有多级结构的月季花状Cu3SnS4微球。粉体用XRD、XPS、FESEM、TEM、UV-Vis和PL进行了表征及光学性能测试。结果表明:粉体Cu3SnS4产品为四方相结构的月季花状微球,球直径约7~10μm,结构稳定性好。微球由一定厚度的片状花瓣从同一成核中心向四周辐射生长组装而成,而花瓣则是由具有单晶结构的纳米薄片通过范德华力堆叠起来的。粉体的室温光致发光测试表明在紫外区出现2个发射带,可能与花球的多级结构有关。并对纳米片-花瓣-微球三级结构的组装机制进行了初步探讨。