Xinli Hao

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.

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.

SiO2 capsulized Cu active nanoparticles: synthesis and activity study

Cu active nanoparticles (Cu ANPs) were synthesized in weakly acidic solution to preserve their catalytic activity. SiO2 capsules were designed to insulate Cu ANPs from oxidation. The weak interaction between SiO2 capsules and Cu ANPs ensured that the designed nanoparticles had good anti-oxidation property and potentially high activity. The increased anti-oxidation property with thicker SiO2 capsules (Cus3 > Cus2 > Cus1) and the order of reactivity to oxygen (Cus1 = Cus2 > Cus3) showed that Cu ANPs with SiO2 capsules (Cus2) of appropriate thickness would be the best for application. By using the samples to construct non-enzymatic sensors, the detected activity toward electro-catalytic oxidation of glucose confirmed this conclusion. Dehiscence of SiO2 capsules recovered the activity of the Cu ANPs in the catalytic ammonium perchlorate (AP) decomposition process. With the addition of 1.5% of Cu ANPs, the high temperature decomposition of AP decreased by 184.2 °C.

Aqueous Synthesis of Mn3O4 Nanoparticle@MnOOH Nanobelt Heterostructures

A combined heterostructures with Mn3O4 nanoparticles attached to MnOOH nanobelts were prepared via an aqueous oxidation method at 90 °C with H2O2 as oxidant. The crystalline structures and morphologies of the as-prepared samples were detected by X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM) analysis, and the forming mechanism of Mn3O4@MnOOH nanomaterials was discussed. Crystalline composition and morphologies of samples changed with reaction time and crystallinity of Mn(OH)2 precursor. β-MnOOH nanoplates can be obtained in the initial reaction, then it transformed to γ-MnOOH nanobelts and/or Mn3O4 nanoparticles as reaction time increasing. The ratio of Mn3O4 in Mn3O4@MnOOH nanomaterials increased with the better crystallinity of Mn(OH)2 precursor. The as-prepared Mn3O4@MnOOH nanomaterials with varied compositions were used for degradation of Rhodamine B (RhB) in acid condition. The degradation reactions carried out in acid condition without stimulated light sources. The results showed that the manganese heterostructures had good activity based on synergy of Mn3O4 and MnOOH nanocrystals.