Synthesis and enhanced photocatalytic activity of regularly shaped Cu 2 O nanowire polyhedra (original) (raw)
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Journal of Materials Science: Materials in Electronics, 2019
In this study, Cu 2 O nanostructures on Cu wire were formed with in situ chemical and then thermal oxidation to obtain the desirable structure, morphology and optical properties in order to enhance visible-light photocatalytic activity. The findings suggested that the procedure involved solution phase treatment and formation of Cu 2 O on pure Cu wire with two-step oxidation in controlled environment of nitrogen and air. Results showed that Cu 2 O nanostructure on Cu substrate were formed from transformation of as-synthesized Cu(OH) 2 nanostructures. The kinetic studies for Cu(OH) 2 formation and the synthesis mechanism of Cu 2 O nanostructures were investigated. The results show that the heterogeneous Cu/Cu 2 O nanostructures display nanorod and polyhedral morphology. The MB degradation reaches 77-82% after 240 min visible light irradiation. The band gap values of the heat treated samples under nitrogen and air were obtained 1.75 and 2.00 eV, respectively. Intensity of PL spectra for the heat treated sample under nitrogen was obviously lower. Furthermore, it is observed that the first order and modified-Freundlich model fit the kinetic data well.
Journal of Materials Science: Materials in Electronics, 2016
The present investigation reports a simple hydrothermal process for synthesizing Cu and CuO nanostructures using new set of low-cost starting reagents including CuSO 4 Á5H 2 O, ethylenediamine and hydrazine hydrate. The obtained nanostructures were characterized by techniques such as XRD, SEM, EDX, DRS and FTIR. Effect of hydrazine hydrate, ethylenediamine, reaction temperature and time on morphology of prepared nanostructures was well studied. Our results showed ethylenediamine and hydrazine hydrate play crucial role on particle growth, formation mechanism of nanostructures and consequently on morphology of nanostructures. Furthermore, the efficiency of CuO nanostructures as a photocatalyst for the decolorization of methylene blue using ultraviolet light irradiation was evaluated and the CuO nanoparticles compared to nanorods showed more efficient photocatalytic activity.
Facile synthesis of Cu@TiO 2 core shell nanowires for efficient photocatalysis
Metallic copper is a dependable co-catalyst for improving photoactivity of TiO 2 photocatalysis. Cu@TiO 2 core shell nanowires (NWs) were prepared by wet chemical synthesis and characterized. The microscopy images clearly show core shell morphology in nano regime. X-ray diffraction studies reveal the metallic copper and anatase TiO 2 crystallinity. The optical absorption spectra exhibit ultraviolet and visible light harvesting properties. X-ray photoelectron spectroscopy confirms the presence of oxidation states of metallic copper and titanium. The photocatalytic efficiency was investigated by degrading the methyl orange (MO) and 3 wt% Cu@TiO 2 core shell NWs shows highest degradation rate (k¼ 0.02905 min À 1) with superior photocatalytic activity. This material could be surely meet the necessities to harvest solar energy for many energy-related applications.
Synthesis and Photocatalytic Properties of CuO-CuS Core-Shell Nanowires
In this study, an efficient method to synthesize CuO-CuS core-shell nanowires by two-step annealing process was reported. CuO nanowires were prepared on copper foil via thermal oxidation in a three-zone horizontal tube furnace. To obtain larger surface area for photocatalytic applications, we varied four processing parameters, finding that growth at 550 • C for 3 h with 16 • C/min of the ramping rate under air condition led to CuO nanowires of appropriate aspect ratio and number density. The second step, sulfurization process, was conducted to synthesize CuO-CuS core-shell nanowires by annealing with sulfur powder at 250 • C for 30 min under lower pressure. High-resolution transmission electron microscopy studies show that a 10 nm thick CuS shell formed and the growth mechanism of the nanowire heterostructure has been proposed. With BET, the surface area was measured to be 135.24 m 2 ·g −1 . The photocatalytic properties were evaluated by the degradation of methylene blue (MB) under visible light irradiation. As we compared CuO-CuS core-shell nanowires with CuO nanowires, the 4-hour degradation rate was enhanced from 67% to 89%. This could be attributed to more effective separation of photoinduced electron and hole pairs in the CuO-CuS heterostructure. The results demonstrated CuO-CuS core-shell nanowires as a promising photocatalyst for dye degradation in polluted water.
Applied Surface Science, 2019
In the present work Cu 2 O shape tailored microcrystals were obtained and investigated. The used shape-tailoring approach was based upon the variation of the starting precursor (copper(II) acetate and copper(II) chloride, the latter one being also much more cheaper and easily accessible), the synthesis temperature (60, 70 and 80°C, respectively) and the shape tailoring agent applied (PVP vs. EDTA). It was found that cubic and polyhedral monodisperse microcrystals were obtained, which showed enhance visible light photocatalytic activity in the degradation of methyl orange. The activity was dependent of the formation of metallic Cu (the formed metallic nanoparticles were obtained when PVP was used), the microcrystals' size and morphology. The band-gap values were directly linkable to the obtained photocatalytic activity, while in the first derivative DRS spectra the electron transition contribution of facet (111) was also found, alongside of the polycrystalline Cu 2 O electron transition contribution. Also, the surface hydrophylicity played a crucial role in the determination of the photocatalytic properties as evidenced by IR measurements and DLS investigations as well.
Applied Surface Science, 2019
In the present work Cu 2 O shape tailored microcrystals were obtained and investigated. The used shape-tailoring approach was based upon the variation of the starting precursor (copper(II) acetate and copper(II) chloride, the latter one being also much more cheaper and easily accessible), the synthesis temperature (60, 70 and 80°C, respectively) and the shape tailoring agent applied (PVP vs. EDTA). It was found that cubic and polyhedral monodisperse microcrystals were obtained, which showed enhance visible light photocatalytic activity in the degradation of methyl orange. The activity was dependent of the formation of metallic Cu (the formed metallic nanoparticles were obtained when PVP was used), the microcrystals' size and morphology. The band-gap values were directly linkable to the obtained photocatalytic activity, while in the first derivative DRS spectra the electron transition contribution of facet (111) was also found, alongside of the polycrystalline Cu 2 O electron transition contribution. Also, the surface hydrophylicity played a crucial role in the determination of the photocatalytic properties as evidenced by IR measurements and DLS investigations as well.
Desalination and Water Treatment, 2015
In this paper, various morphologies of copper oxide (CuO) were synthesized from acetate, sulfate, and nitrate precursors using hydrothermal bath method. The photoluminescence spectra revealed that CuO-Ni sample contains the strongest surface defect peak which can be related to its highest active surface area. The Fourier transform infrared (FT-IR) results showed that the concentration of the surface OH − group on the samples varies considerably according to CuO-Ac > CuO-Ni > CuO-Su. From structural results, it could be observed that all the samples crystallized into a monoclinic crystal structure. The photocatalytic activity of CuO samples was evaluated by the catalytic oxidation of methylene blue in the presence of hydrogen peroxide. Concerning the nearly same optical band gap for the samples, the best photocatalytic performance of CuO-Ni nanorods was assigned to its highest active surface area and surface hydroxyl groups.
Facile synthesis of hierarchical Cu2O nanocubes as visible light photocatalysts
Applied Catalysis B: Environmental, 2016
Hierarchically structured Cu 2 O nanocubes have been synthesized by a facile and cost-effective onepot, solution phase process. Self-assembly of 5 nm Cu 2 O nanocrystallites induced through reduction by glucose affords a mesoporous 375 nm cubic architecture with superior visible light photocatalytic performance in both methylene blue dye degradation and hydrogen production from water than conventional non-porous analogues. Hierarchical nanocubes offer improved accessible surface active sites and optical/electronic properties, which act in concert to confer 200-300% rate-enhancements for the photocatalytic decomposition of organic pollutants and solar fuels.
Synthesis and characterization of nano-CuO and CuO/TiO 2 photocatalysts
Advances in Natural Sciences: Nanoscience and Nanotechnology, 2013
CuO nanocrystals were prepared by thermal decomposition of Cu-oxalate at 400 • C; then CuO/TiO 2 core/shell nanocrystals were formed via the hydrolysis of titanium isopropoxide (TIP) on the surface of CuO nanocrystals. The characteristics of the synthesized nanocrystals were systematically studied using appropriate techniques, namely the morphology by using scanning electron microscopy (SEM), and the crystalline structure by x-ray powder diffraction (XRD) and Raman spectroscopy. The structure, shape and size of the CuO and CuO/TiO 2 nanocrystals could be tuned by changing various technological parameters: (i) the reaction/growth time (from several minutes to several hours), (ii) reaction temperature (from room temperature to 90 • C) and (iii) the molar ratios of the precursors. The results showed that the reaction temperature and the molar ratio of the precursors play important roles in controlling the morphology and size of both CuO and CuO/TiO 2 nanocrystals. With increasing reaction temperature, nano-CuO evolved from spherical shaped nanoparticles to microspheres. By shelling the large-bandgap TiO 2 layers on CuO nanocrystals, the core/shell structure is formed and the narrow-bandgap nano-CuO core is expected to be resistant to photocorrosion.