摘要：
Well dispersed CuO nanoflakes were successfully achieved via a fast and self-heating route. The physical properties of the as-prepared products were analyzed by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), nitrogen adsorption-desorption measurements, transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Meanwhile, the catalytic activity and the catalytic advantage of CuO nanostructures are discussed with the help of first-order kinetics investigation for methylene blue degradation. It is found that self-heating in the reaction mixture and formation of cellular CuO network fully filled with oxygen bubble are mainly responsible for synthesis of CuO nanoflakes. Meanwhile, the as-obtained CuO nanoflakes possessed high specific surface area and exhibited high catalytic characteristics with wet hydrogen peroxide oxidation in methylene blue solution. The present work is likely to be favorable for taking full advantage of the catalytic activity of CuO nanostructures with high specific surface area for the wet hydrogen peroxide oxidation of dyes.
摘要：
In this work, a facile one-step hydrothermal route was demonstrated for the fabrication of Cu/Cu2O composite nanowires. Metallic Cu nanoparticles were formed via in-situ reduction on the surface of Cu2O nanowires. The investigation of scanning electron microscopy and transmission electron microscopy revealed that well-defined Cu/Cu2O composite nanowires, with diameters around 60 nm and lengths of about several microns, were formed at 100 degrees C in the presence of PVP with glucose as a reductant. Moreover, Cu nanoparticles, with diameters less than 30 nm, were highly dispersed and strongly anchored on the surface of Cu2O nanowires, forming close contact. We found that PVP played a key role in the anisotropic growth of Cu/Cu2O nanowires. The mechanism was briefly discussed. The as-prepared Cu/Cu2O composite nanowires with a suitable amount of Cu showed a further improvement on the photocatalytic efficiency for degradation of MB, probably due to the Schottky junction formed at the interface between Cu2O and metallic Cu, and the Surface plasmon resonance of metallic Cu nanoparticles.
摘要：
In this study, BiVO4@Cu2O core-shell n-p heterojunctions based on BiVO4 nanospheres were synthesized via a template-free hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) analyses confirmed the core-shell structure of the as-obtained samples. A possible mechanism of Cu2O shell formation on the surface of BiVO4 nanosphere was proposed based on the characterization results, which involved a deposition-reduction-crystallization process. The as-prepared BiVO4@Cu2O core-shell nanospheres exhibited enhanced photocatalytic activity compared to BiVO4 and Cu2O on the degradation of Rhodamine B under visible light irradiation, which could be attributed to the synergic effect on the separation and transfer of electrons and holes at the interface of BiVO4 and Cu2O. The possible photocatalytic mechanism was proposed based on the experimental results and calculated energy band positions.
摘要：
Ni3S2@Ni composite electrode for supercapacitor is synthesized via a one-step solvothermal treatment of Ni foam at 120 degrees C, exhibiting a 3D meso/macroporous network structure. The structure contains Ni3S2 nanosheets with 15-20 nm in thickness and meso/macropores with an average pore size of 24.69 nm, and its formation is regulated through the slow release of S2- ions and the solid/liquid interfacial reactions in absolute ethanol. At a current density of 17.15 A g(-1), the composite electrode demonstrates a high specific capacitance of 945.71 F g(-1), and at various current densities below 17.15 A g(-1), it retains capacitance retention ratios above 100% after 2000 charge/discharge cycles. A two-step oxidation and three-step reverse reduction process occurs during the reversible Faradaic reaction of Ni3S2 in KOH aqueous solution, which is due to the valence transitions of Ni-0 in Ni3S2 between Ni-0 and Ni3+. The homogeneous cracking in Ni3S2 layer is a critical factor for achieving its long-term cycling stability, however, the cycling results in its amorphization. An asymmetric supercapacitor is assembled using Ni3S2@Ni composite electrode as the positive electrode and Ni foam as the negative electrode, which delivers an energy density of 55.79 Wh kg(-1) at the power density of 938.98 W kg(-1). (c) 2018 Elsevier Ltd. All rights reserved.
摘要：
Fe-doped BiVO_4 with hierarchical flower-like structure was prepared via a hydrothermal method using sodium dodecyl benzene sulfonate (SDBS) as structure directing agent. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM), X-ray photoelectron spectroscopy (XPS) and UV-Vis were applied for characterization of the as-prepared samples. The formation mechanism of flower-like structure was proposed based on the evolution of morphology as a function of hydrothermal time. Fe-doped into substitutional sites of BiVO_4 effectively improved the migration and separation of photogenerated carrier and enhanced the utilization of visible light. Flower-like Fe-doped BiVO_4 showed much higher visible-light-driven photocatalytic efficiency for degradation of methyl blue compared with the pristine BiVO_4. And the sample with a Fe/Bi mole ratio of 2.5% showed the highest photocatalytic efficiency.
摘要：
Monoclinic BiPO_4 with rod-like shape was prepared via a CTAB-assisted hydrothermal route. MnO_x nanoparticles were loaded on the surfaces of BiPO_4 rods by a photo-deposition process to form MnO_x/BiPO_4 heterojunctions. The as-prepared samples were characterized by XRD, SEM, TEM, XPS, FL, and UV-Vis diffuse reflectance measurements. The results showed that MnO_x nanoparticles were strongly anchored to the surfaces of BiPO_4 rods when the mole ratio of Mn to Bi was controlled at a low level, forming MnO_x/BiPO_4 heterojunctions with effective and sound interfaces. The MnO_x/BiPO_4 heterojunctions exhibited higher photoactivity than pristine BiPO_4 for photodegradation of methyl blue under UV irradiation, which could be attributed to the efficient charge transfer at the heterojunction interfaces. The higher light absorption ability of MnO_x/BiPO_4 in the range of 300–420 nm compared with pristine BiPO_4 was also responsible for the enhanced photocatalytic activities of MnO_x/BiPO_4 heterojunctions.
