Jingzhe Zhao

Room temperature synthesis of 2D CuO nanoleaves in aqueous solution

A simple room temperature method was reported for the synthesis of CuO nanocrystals in aqueous solution through the sequence of Cu(2+) → Cu(OA)2 → Cu(OH)2 → Cu(OH)(2-)4 → CuO. Sodium oleate (SOA) was used as the surfactant and shape controller. The as-prepared samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectroscopy (UV-vis) and differential thermal analysis (DTA). It can be seen that 1D Cu(OH)(2) nanowires were first obtained from Cu(OA)(2) and, at room temperature, converted into 2D CuO nanoleaves (CuO NLs) in a short time under a weakly basic environment. On prolonging the reaction time, the top part of these 2D nanoleaves branched and separated along the long axis to form 1D rod-like nano-CuO because of the assistance of SOA. A possible transformation mechanism of Cu(OH)(2) to CuO nanostructures at room temperature in aqueous solution is discussed. The transformation velocity can be controlled by changing the pH value of the system. The prepared CuO NLs were used to construct an enzyme-free glucose sensor. The detecting results showed that the designed sensor exhibited good amperometric responses towards glucose with good anti-interferent ability.

Photoluminescent properties of ZnS:Mn nanocrystals prepared in inhomogeneous system

Abstract ZnS:Mn nanocrystalline colloids and powders were prepared by chemical method with H 2 S gas in an inhomogeneous system of gas–liquid phase. The best reactive conditions were determined. The structure and the properties of the materials were examined by X-ray diffraction (XRD) and infrared (IR) spectroscopy. From the PLE and PL spectra of ZnS:Mn nanocrystals, it is shown that the Mn 2+ ions are incorporated into the ZnS host structure. The position of the characteristic peaks in the PLE spectra of ZnS:Mn nanocrystal sol or powders shift to higher energy under UV exposure, and are different from those of ZnS:Mn bulk materials. The emission sites of ZnS:Mn nanocrystal sol and powders are different from the bulk materials, but the emission sites of nanocrystal powders are the same as those of nanocrystal sol.

Preparation, characterization and catalytic activity of sulfated zirconia–silica nanocrystalline catalysts

Abstract Sulfated zirconia–silica (SO42−/ZrO2–SiO2) precursors were prepared by chemical methods in three steps. The precursors were calcinated at different temperatures to form the SO42−/ZrO2–SiO2 nanocrystalline catalysts. The reaction conditions were optimized, such as ZrO2 content, volume ratio of water–ethanol, amount of HNO3 and reactive temperature and time. The specific surface area, heat stability and structure properties of catalysts were examined by X-ray diffraction (XRD), IR and differential thermal analysis (DTA). The specific surface areas of ZrO2–SiO2 and SO42−/ZrO2–SiO2 are 800 and 400 m2/g, respectively. They are higher than that of ZrO2 and SO42−/ZrO2. It was shown that there are very strong interactions between SO42− and ZrO2–SiO2. The acidic properties of SO42−/ZrO2–SiO2 were tested by Hammett indicator method. Through the acetic acid (HAc) reaction with glycerin, it was shown that the SO42−/ZrO2–SiO2 catalyst has highly active sites and high catalytic activity.

The synthesis and characterization of TiO2/wollastonite composite

Abstract TiO2/wollastonite composites were prepared by precipitating titania on the surface of wollastonite. Wollastonite powders must age for a few hours in titanium sulfate solutions before the formation of the film of titania. Increasing the reaction temperature is not of benefit to produce titania fully coated on wollastonite. The characterization of composites was made by XRD, IR, UV, SEM and EES methods. All the results reveal that the properties of composites are similar to that of titania, and the thermal stability of composites is better than that of titania powders.

12-tungstophosphoric heteropolyacid anions encapsulated in chemically modified mesoporous silica FSM-16 and its electrocatalytic reduction for nitrite

Abstract 12-Tungstophosphoric heteropolyacid anions (denoted PW 12 ) have been successfully immobilised on chemically modified mesoporous silica FSM-16 (denoted FSM-16 (m) ). The complex PW 12 /FSM-16 (m) was characterized by IR, XRD, spectrum NMR and CV. The results show the framework of FSM-16 is retained upon inserting the guest compound and the composite is an active electrocatalyst for the reduction of NO 2 − .

Synthesis and catalytic activity of stable hollow ZrO2–SiO2 spheres with mesopores in the shell wall

Stable hollow ZrO2–SiO2 spheres with mesopores in the shell wall have been successfully synthesized by a sol–gel process in an oil–water–oil microemulsion. The samples were characterized by transmission polarized light microscopy, SEM, TEM, and N2 adsorption–desorption isotherms. The characterization results indicate that a large number of mesopores are present in the shell wall of the calcined hollow ZrO2–SiO2 spheres, and that the diameter and shell thickness are ca. 50 and 15 µm, respectively. The hollow spheres exhibit high thermal stability and remain intact spherical structures even after calcination at 550 °C for 8 h. In the cracking reactions of cumene and 1,3,5-triisopropylbenzene the sulfated hollow ZrO2–SiO2 spheres show very high catalytic activities. Especially, the higher catalytic activity of 1,3,5-triisopropylbenzene cracking suggests the potential application in cracking of bulky molecules. A possible formation mechanism of hollow spheres of binary composite oxide is also proposed.

Facile and Efficient Synthesis of Bismuth Nanowires for Improved Photocatalytic Activity

An aqueous reduction method was reported for the synthesis of bismuth nanowires (Bi NWs) 5-10 nm in diameter and several micrometers in length under the guidance of PVP molecules. The reactions were performed at 80 °C by reducing bismuth chloride with sodium hypophosphite first in acid and then under neutral circumstances. The key to successful preparation of the Bi NWs is regulation of the reduction speed by control of the pH value. The morphology evolution of the samples was also found to have a strong dependence on the reaction parameters, including the introduction amount and molecular weight of PVP molecules. A solid-solution-solid (SSS) mechanism was proposed for the nucleation and growth of Bi NWs in our strategy. The as-prepared Bi NWs exhibit excellent visible-light photocatalytic activities for the degradation of the organic pollutant Rhodamine B (RhB) and colorless bisphenol A (BPA). The good recyclability of the Bi NWs on RhB photodegradation demonstrates the possibility of their practical applications.

Preparation of stable mesoporous silica FSM-16 from water glass in the presence of cetylpyridium bromide

The synthesis and characterization of the mesoporous materials FSM-16 (folded sheets mesoporous materials) with highly ordered structure in open-vessel by using cetylpyridium bromide (CPBr) and the single-layered polysilica Kanemite as new template and silicon source, respectively, has been investigated systematically. The hexagonal arrangements of uniformly size pores were characterized by FTIR. XRD. nitrogen adsorption. TG-DTA. SEM and TEM. Especially, the porous products with higher surface areas show remarkable thermal stability up to 1000 C. The potential application as carrier of catalysts or host-guest materials is anticipated

Assembled and isolated Bi5O7I nanowires with good photocatalytic activities

Assembled and isolated Bi5O7I nanowires were fast prepared through an aqueous strategy without further complex treatment. Powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-vis diffuse reflectance spectroscopy (DRS) were used to characterize the obtained samples and reveal the evolution process of Bi5O7I nanomaterials. The formation of a hierarchical BiOI precursor and fast substitution of I− with OH− facilitated the evolution of assembled Bi5O7I architectures, while isolated Bi5O7I nanowires were obtained by shortening the existence time of BiOI crystals on the basis of assembled Bi5O7I nanowires. HRTEM results revealed similar crystalline orientations of nanowires along the [010] direction for the assembled and isolated Bi5O7I nanowire samples. And the nanowires in an assembled sample also exhibited a superlattice-like structure with a periodicity of 0.84 nm. On comparison to the BiOI precursor, the Bi5O7I nanowires with different assembly-styles all displayed good photocatalytic activities on the degradation of rhodamine B (RhB) dye and colorless bisphenol-A (BPA) under visible-light irradiation. The photocatalytic efficiency reached 96% in 3 h for RhB and 90% in 4 h for BPA in the degradation system at pH = 7. The assembled nanowire samples showed even better photocatalytic activities on the degradation of model organic pollutants relative to the isolated nanowire samples. Band structures and trapping experiments were studied to reveal the degradation mechanism over Bi5O7I nanowire samples. It was proposed that a valid separation of photogenerated electrons and holes and appropriate valence and conduction band positions of Bi5O7I nanowires led to good visible-light-induced catalytic properties.

Facile solution-based synthesis and optical properties of Co 3 O 4 nanoparticles at low-temperature

Cobalt oxide(Co3O4) with different morphologies was achieved by a simple solution-based method. Various parallel experiments show that several experimental parameters, such as the concentrations of NaOH and ethylene glycol(EG), play important roles in the morphological controlling of Co3O4 nanoparticles. A lower concentration of NaOH favors quasi-spherical product with a uniform size of about 15 nm, whereas a higher concentration of NaOH generally leads to the formation of nanoplates with wide size distribution. In addition, Co3O4 nanorods were also obtained partially by introducing a certain amount of EG. A possible mechanism was proposed for the selective formation of Co3O4 with various morphologies. X-Ray diffraction(XRD), infrared(IR) spectrometry, scanning electron microscopy(SEM), transmission electron microscopy(TEM) and UV-Vis spectrometry were used to characterize the samples.