Synthesis of CuO Nanorods, Reduction of CuO into Cu Nanorods, and Diffuse Reflectance Measurements of CuO and Cu Nanomaterials in the Near Infrared Region
ABSTRACT CuO nanorods were synthesized by hydrothermal methods with three different chemical combinations: (i) copper nitrate, lactic acid, and sodium hydroxide; (ii) copper sulfate, sodium lactate, and sodium hydroxide; and (iii) copper nitrate and sodium hydroxide. Physical parameters, concentration, temperature, and aging time, greatly affected the size and morphology of the nanorods; CuO nanoparticles were also prepared. These nanorods and nanoparticles were reduced to metallic copper at elevated temperature by 4% H2 diluted in helium. The morphology of CuO nanomaterials (nanorods and nanoparticles) was preserved after reduction. These CuO and Cu nanorods and nanoparticles were characterized by XRD, SEM, TEM, SEM-EDS, and BET measurements. The CuO and Cu nanomaterials were employed for near-infrared (NIR) diffuse reflectance. Among these materials, CuO nanorods were to be found the best NIR diffuse reflectors, indicating potential application as NIR obscurants.
SourceAvailable from: PubMed Central[Show abstract] [Hide abstract]
ABSTRACT: Different cupric oxide (CuO) structures have attracted intensive interest because of their promising applications in various fields. In this study, three kinds of CuO structures, namely, CuO microdisks, CuO nanoblocks, and CuO microspheres, are synthesized by solution-based synthetic methods. The morphologies and crystal structures of these CuO structures are characterized by field-emission scanning electron microscope and X-ray diffractometer, respectively. They are used as thermal conductive fillers to prepare silicone-based thermal greases, giving rise to great enhancement in thermal conductivity. Compared with pure silicone base, the thermal conductivities of thermal greases with CuO microdisks, CuO nanoblocks, and CuO microspheres are 0.283, 0256, and 0.239 W/mK, respectively, at filler loading of 9 vol.%, which increases 139%, 116%, and 99%, respectively. These thermal greases present a slight descendent tendency in thermal conductivity at elevated temperatures. These experimental data are compared with Nan's model prediction, indicating that the shape factor has a great influence on thermal conductivity improvement of thermal greases with different CuO structures. Meanwhile, due to large aspect ratio of CuO microdisks, they can form thermal networks more effectively than the other two structures, resulting in higher thermal conductivity enhancement.Nanoscale Research Letters 01/2015; 10:113. DOI:10.1186/s11671-015-0822-6 · 2.52 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: p-CuO thin films have been synthesized on Indium Tin Oxide (ITO) coated glass substrates and on ZnO/ITO coated glass substrates using a new, simple, cost-effective electrochemical technique (Galvanic deposition) at room-temperature. X-ray Diffraction Technique (XRD) of the films show monoclinic phase of CuO and UV-vis spectroscopy of the CuO/ITO film shows indirect band-gap energy of about 1.85 eV. The surface morphology of CuO thin film consists of a c-axis grown regular macro porous network structure with deep cavities surrounded by thin solid walls, suitable for gas trapping and sensing. Current-Voltage characteristics of the formed p-CuO / n-ZnO film show good rectifying behavior. At 1 V reverse bias the leakage current density was as low as 2 x 10-9 A compared to the current 1.2 x 10-7 A at the same forward bias resulting in a forward-to reverse current ratio of about 60. The ideality factor of the diode was obtained to be quite as high of about 9.5. The frequency dependence of the small signal AC response in the both Rp – Cp and Rs – Cs mode of the fabricated hetero-junction were measured at a reverse bias of 1.5 V. In the presence of 10000 ppm gas exposure for gases like CH4, H2S and CO, frequency dependent changes in AC responses are different for different gases. The variation of the reactance of the fabricated device show different behaviour with exposure to different types of gases. The minimum in reactance occurs at different frequencies for different gases indicates the selectivity of the device for gas sensing.RSC Advances 09/2014; 4(93). DOI:10.1039/C4RA05360E · 3.71 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: 1D CuO nanorods have been successfully prepared in the presence of a metal ion containing ionic liquid, namely bis(1-hexadecyl-3-methylimidazolium) tetrachlorocuprate ([C16mim]2CuCl4) under solvothermal conditions. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), FTIR spectroscopy and the Brunauer-Emmet-Teller (BET) surface area method. The nanorods synthesized from metal ion containing ionic liquids showed good crystallinity, well-defined morphologies, small sizes and large BET surface areas. The effect of changing the alkyl chain length of the ionic liquid's cation on the morphology of CuO has been investigated. It was found that the ionic liquid acted not only as a Cu source but also as a solvent and template for the fabrication of 1D CuO nanorods. In addition, the capacitance of CuO as an electrode material was tested by cyclic voltammetry and chronopotentiometric measurements. With the morphologies changing from nanoparticles to nanorods, the BET surface area of CuO was significantly increased from 38.79 m2 g–1 to 88.46 m2 g–1 and the specific capacitance of CuO also increased from 58.25 F g–1 to 498.75 F g–1. Thus, the CuO nanorods are promising for the future development of supercapacitors.Berichte der deutschen chemischen Gesellschaft 05/2013; 2013(13). DOI:10.1002/ejic.201201068