Synthesis and Characterization of SnO<SUB>2</SUB>Flower-Shaped by Hydrothermal Route for Formaldehyde Sensing Properties

In this work, we’ve made SnO2 flower formed with the aid of using easy test steps, and without cost, which is the hydrothermal approach and without a template. We have used a variety of techniques to characterize SnO2 flower-shaped by (SEM, TEM, XRD, BET and XPS) instruments. Confirmatory tests carried out have proven that the surface of the tetragonal structure of SnO2 has a rough surface which makes it excellent for its gas-sensing properties. The gas detection test of SnO2 flower-shaped proved that it possesses the selectivity of formaldehyde gas (about 30), the optimum operating temperature of the sensor is 220°C, and also the sensor has a high response time and recovery time is (5 s and 22 s) to 100 ppm, respectively. Particularly, the sensor has an obvious response value (2) when exposed to 5 ppm formaldehyde. As well, the mechanism of gas-sensing was also discussed.

Effect of Hydroxide Ion Concentration on the Morphology of the Hydroxyapatite Nanorods Synthesized Using Electrophoretic Deposition

The effect of OH- concentration on the morphology of the hydroxyapatite (HA) nanorod synthesized using electrophoretic deposition (EPD) method has been investigated. The growth of HA nanorods was achieved on polished titanium substrates. The electrolyte used in this study was prepared by dissolving calcium acetate (Ca (CH3COO)2H)2O), and Ammonium dihydrogen phosphate (NH4H2PO4) in distilled water without any surfactant, and was maintained at 80-130°C. Two electrolytes with OH- concentration of 10-4 and 10-10 were prepared. A highly homogeneous HA nanorods deposited on the titanium substrates were obtained after 1 h in the electrolytes with higher OH- concentration of 10-4. On the other hand, a flower-shaped HA nanostructures composed of needle-like HA crystals were obtained in the electrolyte of lower OH- concentration of 10-10. The deposits were identified as HA crystal rods grown along the c axis and perpendicular to the substrate. The HA deposits were characterized by scanning electron microscopy (SEM) while detailed structural characterization was done using a transmission electron microscope (TEM) equipped with selected area electron diffraction (SAED) patterns.

MOF-derived spherical Ni_(x)S_(y)/carbon with B-doping enabling high supercapacitive performance

This work uses a simple Ni-metal organic framework(Ni-MOF)to generate a uniform metal-containing carbon hybrid structure of Ni/C by in-situ pyrolysis.Then,after NaBH_(4) treatment and hydrothermal vul-canization of Ni/C,multiphase B-doped Ni_(x)S_(y) nanoparticles can be obtained and uniformly anchored in the carbon skeleton,forming a highly porous flower-shaped B-Ni_(x)S_(y)/C composite.The positive role of B doping was theoretically confirmed by Density Function Theory(DFT)calculations.The MOF-derived car-bon framework has porous,conductive,and continuous features beneficial for fast charge transfer.There are also multiple Ni-sulfide phases in B-Ni_(x)S_(y)/C,dominated by hexagonal NiS,hexagonal Ni 2 S 3,and cu-bic Ni_(3)S_(4),which give rich valance state and are expected to bring active electrochemical reactions.In addition,the boronation process by the reducing agent of NaBH_(4) is also proved beneficial to bring high capacitance,possibly due to the incorporation of more active sites by B.Therefore,the B-Ni_(x)S_(y)/C compos-ite electrode delivers a high specific capacity of 1250.4 C g^(-1) at 1 A g^(-1) and excellent rate performance.The B-Ni_(x)S_(y)/C-based asymmetric supercapacitor also shows promising prospects for future energy stor-age devices,delivering high cyclability with capacitance retention of 87.6%after 7000 cycles.This work proves the efficiency of MOF-derived carbon framework and B-doping in improving metal sulfide’s electrochemical performances.

Self-assembly of Ophiopogonis polysaccharide-iron(Ⅲ) complex in aqueous solution and solid state

Ophiopogonis polysaccharide-iron(Ⅲ)(OPI)was prepared and characterized in the present study.The optimum condition for preparing OPI was as follows:OP and trisodium citrate were mixed at a weight ratio of 4:1 and reacted in a water bath at 70°C for 3 h within the pH range of 8.0–8.5.Aggregation morphology or structure of OPI in aqueous solution and solid state was studied by scanning electron microscopy,transmission electron microscopy and small-angle X-ray diffraction.In aqueous solution,OPI could self-assemble into micron vesicles with flower-shaped morphology.Results of X-ray diffraction showed OPI with layered structure.A core-shell model was proposed for OPI.