CuO Nanorods Research Articles

Facile synthesis of CuO nanorods obtained without any template and/or surfactant

Abstract High-aspect ratio CuO nanorods (with diameter of ~ 10 nm) were obtained via a simple colloidal precipitation method. The process did not involve any surfactant or pre-existing templates; a strategy generally adopted for obtaining shape-controlled nanostructures. CuO nanostructures, as synthesized at 110 °C, were fully crystalline and depicted a monoclinic structure. The phase-purity along with the homogeneity of their nanoscale dispersion was validated via various structural characterization techniques. Synthesis mechanism for the nanorods relied on the effect of strong alkaline medium which in turn promoted the directional growth of the CuO nanostructures. The distinct advantages (low cost, surfactant-free shape control, speed and ease of synthesis at lower temperature, generous yield, high surface area etc) of our synthesis process confirm its potential to be used for advanced functional applications. Efficiency of the CuO nanorods was also confirmed for catalytic applications involving waste water treatments; UV–visible spectroscopic measurements confirmed the degradation of toxic nitrophenol in 15 min.

Facile synthesis of Cu2O nanorod arrays on Cu foam as a self-supporting anode material for lithium ion batteries

In the present work, we have successfully fabricated three-dimensional Cu2O nanorod arrays on Cu foam by an efficient solvothermal approach followed by a post-annealing treatment with using PVP as a reducing agent. These materials were further investigated as binder- and conductive-agent-free anodes for lithium-ion batteries. It was found that the Cu2O nanorod arrays on Cu foam exhibited excellent cycle performance with negligible capacity fading, high reversible capacity, and superior rate capability compared with commercial Cu2O nanoparticles.

CuO Nanorod Arrays Formed Directly on Cu Foil from MOFs as Superior Binder-Free Anode Material for Lithium-Ion Batteries

In this study, an in situ growth method is developed for the partial conversion of current collector into active materials for lithium ion batteries (LIBs). Through thermal treatment of a metal–organic framework (MOF) precursor, of which the metal ion is provided by a Cu foil current collector, porous CuO nanorod arrays (NRAs) can be directly formed on Cu foil. Importantly, this strategy can avoid the poor contact problem between the current collector and electrode material as well as circumvent the addition of insulating material (binder) and inhomogeneous distribution of conductive carbon material and active material on the current collector. When evaluated as binder-free electrodes for LIBs, porous CuO NRAs deliver a high specific capacity (1341 mA h g–1 at 100 mA g–1) and enhanced rate capability and cycling ability (671 mA h g–1 at 100 mA g–1 after 150 cycles).

Enhanced catalytic activity of mesoporous graphitic carbon nitride on thermal decomposition of ammonium perchlorate via copper oxide modification

Aiming at enhancing the catalytic activity of mpg-C3N4 on thermal decomposition of ammonium perchlorate, mpg-C3N4 was successfully modified by CuO nanorods, via a facile precipitation method. The structure, morphology and composition of mpg-C3N4 and mpg-C3N4/CuO nanocomposites were characterized by nitrogen adsorption-desorption measurements, transmission electron microscopy, scanning electron microscope, X-ray power diffraction, fourier transform infrared spectroscopy, as well as X-ray photoelectron spectroscopy. The results demonstrated that CuO nanorods (length of 200–300nm, diameter of 10–15nm) were uniformly dispersed throughout mpg-C3N4, efficiently avoiding the agglomeration. Finally, it was demonstrated that the high weight-loss decomposition temperature of AP was decreased up to 118.5°C in the presence of 2wt% mpg-C3N4/CuO nanocomposites, which was higher than that of pure mpg-C3N4 and CuO, respectively, demonstrating the catalytic performances of the nanocomposites was enhanced via the synergistic catalysis between mpg-C3N4 and CuO.

Direct Growth of CuO Nanorods on Graphitic Carbon Nitride with Synergistic Effect on Thermal Decomposition of Ammonium Perchlorate.

Novel graphitic carbon nitride/CuO (g-C3N4/CuO) nanocomposite was synthesized through a facile precipitation method. Due to the strong ion-dipole interaction between copper ions and nitrogen atoms of g-C3N4, CuO nanorods (length 200–300 nm, diameter 5–10 nm) were directly grown on g-C3N4, forming a g-C3N4/CuO nanocomposite, which was confirmed via X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). Finally, thermal decomposition of ammonium perchlorate (AP) in the absence and presence of the prepared g-C3N4/CuO nanocomposite was examined by differential thermal analysis (DTA), and thermal gravimetric analysis (TGA). The g-C3N4/CuO nanocomposite showed promising catalytic effects for the thermal decomposition of AP. Upon addition of 2 wt % nanocomposite with the best catalytic performance (g-C3N4/20 wt % CuO), the decomposition temperature of AP was decreased by up to 105.5 °C and only one decomposition step was found instead of the two steps commonly reported in other examples, demonstrating the synergistic catalytic activity of the as-synthesized nanocomposite. This study demonstrated a successful example regarding the direct growth of metal oxide on g-C3N4 by ion-dipole interaction between metallic ions, and the lone pair electrons on nitrogen atoms, which could provide a novel strategy for the preparation of g-C3N4-based nanocomposite.

Solid‐Liquid Interface Based Biphasic Reaction for Nanomaterial Preparation: Bundled CuO Nanorods as an Example and Their Outstanding Photocatalytic Efficiencies

AbstractFor the first time, a novel environmentally friendly solid‐liquid interface based biphasic reaction process for preparation of nanostructured oxide materials was developed. The process was demonstrated to produce bundled CuO nanorods, which were further shown to be an outstanding catalyst for sun‐light assisted heterogeneous Fenton processes for degradation of RhB, a model recalcitrant organic pollutant.

Room temperature growth and field emission characteristics of CuO nanostructures

A variety of CuO nanostructures have been synthesized directly on copper foils by room temperature oxidation of copper through wet chemical method. Alkaline condition necessary for the growth process was maintained by the application of NaOH and NH3 precursors. pH of the solution and reaction time were selected as the process variables. Formation of CuO was confirmed by X-ray diffraction pattern analysis. Evolution of morphologies of the phases formed was characterized by field emission scanning electron microscopy, leading to elucidation of the growth mechanism. Different types of CuO nanostructures were observed to be formed at different process parameters, selected for the present study. Field emission characteristics of CuO nanorods and CuO nanoflakes were also investigated. Emission current density of CuO nanorods and CuO nanoflakes were determined to be 0.90 mA/cm2 and 0.48 mA/cm2, respectively. Huge difference in the emission current density indicates that field emission properties of CuO nanostructures are strongly affected by their morphology.

Fabrication of mesoporous CuO/ZrO2-MCM-41 nanocomposites for photocatalytic reduction of Cr(VI)

Mesoporous nanocomposites of CuO/ZrO2–MCM-41 (CuO@ZM-41) was designed by incorporating mesoporous ZrO2 (Z) into the high surface area MCM-41 (M-41) framework followed by loading CuO by wetness impregnation method keeping Si/Zr ratio 10. The nanocomposites were studied under PXRD, N2 sorption, DRS spectra, FTIR, XPS, NMR, HRTEM and PL to evaluate structural, morphological, optical properties and also the mesoporosity nature of the samples. The photo-reduction of Cr6+ was performed over CuO@ZM-41 by varying pH, substrate concentration, and irradiation time and catalyst dose. Among all the catalysts, 2 CuO@ZM-41 was found to be efficient photocatalyst for the photo-reduction of Cr6+. Nearly 100% reduction of Cr6+ has been achieved by 2 CuO@ZM-41 within 30min. Intra-particle mesoporosity, high surface area, presence of CuO nanorods and electron transfer properties are the key factors for enhancing the photo-reduction activity of 2CuO@ZM-41.

Phosphorus-doped silicon nanorod anodes for high power lithium-ion batteries.

Heavy-phosphorus-doped silicon anodes were fabricated on CuO nanorods for application in high power lithium-ion batteries. Since the conductivity of lithiated CuO is significantly better than that of CuO, after the first discharge, the voltage cut-off window was then set to the range covering only the discharge–charge range of Si. Thus, the CuO core was in situ lithiated and acts merely as the electronic conductor in the following cycles. The Si anode presented herein exhibited a capacity of 990 mAh/g at the rate of 9 A/g after 100 cycles. The anode also presented a stable rate performance even at a current density as high as 20 A/g.

Controlled synthesis of hierarchical Cu nanosheets @ CuO nanorods as high-performance anode material for lithium-ion batteries

The hierarchical Cu nanosheets @ CuO nanorods nanostructures were fabricated by a facile hydrothermal approach using Cu nanosheets as self-template and nano-substrate in an aqueous solution of NaOH/H2O2. The hierarchical Cu nanosheets @ CuO nanorods electrodes show a high reversible capacity of 620mAh/g after 200 cycles, much higher than that of the pure CuO nanocrystals at a current 0.1C. The excellent electrochemical performance of the hierarchical Cu nanosheets @ CuO nanorods electrode can be attributed to the unique architecture, which not only provides appropriate spaces between nanorod arrays to accommodate the volume change during the discharge/charge process, but also enables fast charge transport owing to the reduced diffusion paths for electrons and induced the Cu nanosheet as the nano-substrates.

Hydrogen gas detection of Nb2O5 nanoparticle-decorated CuO nanorod sensors

Pristine and Nb2O5 nanoparticles-decorated CuO nanorods were prepared successfully by a two step process: the thermal evaporation of a Cu foil and the spin coating of NbCl5 solution on CuO nanorods followed by thermal annealing. X-ray diffraction was performed to examine the structure and purity of the synthesized nanoatuctures. Scanning electron microscopy was used to examine the morphology and shape of the nanostuctures. The Nb2O5 nanoparticles-decorated CuO nanorod sensor showed responses of ~217.05-862.54%, response times of ~161-199 s and recovery times of ~163-171 s toward H2 gas with concentrations in a range of 0.5 - 5% at the optimal working temperature of 300 °C. The Nb2O5 nanoparticle-decorated CuO nanorod sensor showed superior sensing performance to the pristine CuO nanorod sensor for the same H2 concentration range. The underlying mechanism for the enhanced hydrogen sensing performance of the CuO nanorods decorated with Nb2O5 nanoparticles is discussed.

Highly-reactive Al/CuO nanoenergetic materials with a tubular structure

Al/CuO nanoenergetic materials with nanotube and nanorod morphologies were prepared and investigated in this study. The CuO nanotubes and nanorods synthesized by chemical etching are homogenous on a large scale, with an external diameter in the range of 100–200nm and typical lengths of 5–7μm. Each of these CuO nano-arrays was deposited on nano-Al by electrophoretic deposition. Using the Brunauer-Emmett-Teller method, the Al/CuO nanotube composite is determined to have a larger specific surface area (43.20m2/g) than that of the Al/CuO nanorod composite (16.75m2/g). The energy released from the Al/CuO nanotubes is approximately to 3264J/g, which is higher than that released from the Al/CuO nanorods (2013J/g). The combustion flames for the Al/CuO nanotubes are also more rapid and violent. It is speculated that the excellent output of energy and outstanding combustion performance of the Al/CuO nanotubes could be ascribed to their tubular architecture, which has a larger specific surface area enhances the intimate contact and mass transmission between fuel and oxide.

CuO Nanorods-Decorated Reduced Graphene Oxide Nanocatalysts for Catalytic Oxidation of CO

Developing an efficient non-noble catalyst for CO oxidation with high catalytic activity remains a challenge for practical applications. In this work, CuO nanorods decorated reduced graphene oxide (RGO) nanocatalysts were prepared via a facile one-step hydrothermal method. The structure and morphology of the as-prepared samples were characterized by XRD, Raman spectroscopy, SEM, TEM, and X-ray photoelectron spectroscopy (XPS). The analysis results show that CuO nanorods were successfully deposited on the surface of RGO sheets with the length of 250–500 nm. The catalytic properties of the as-prepared catalysts for CO oxidation were evaluated by using a microreactor-gas chromatograph (GC) system. The as-prepared RGO–CuO nanocatalysts exhibited high activity for CO oxidation, and the 10 wt % reduced graphene oxide content catalyst can achieve CO total oxidation at 165 °C.

Physical Confinement Promoting Formation of Cu2O–Au Heterostructures with Au Nanoparticles Entrapped within Crystalline Cu2O Nanorods

Building on the application of cuprite (Cu2O) in solar energy technologies and reports of increased optical absorption caused by metal-to-semiconductor energy transfer, a confinement-based strategy was developed to fabricate high aspect ratio, crystalline Cu2O nanorods containing entrapped gold nanoparticles (Au nps). Cu2O was crystallized within the confines of track-etch membrane pores, where this physical, assembly based method eliminates the necessity of specific chemical interactions to achieve a well-defined metal–semiconductor interface. With high-resolution scanning/transmission electron microscopy (S/TEM) and tomography, we demonstrate the encasement of the majority of Au nps by crystalline Cu2O and show crystalline Cu2O–Au interfaces that are free of extended amorphous regions. Such nanocrystal heterostructures are good candidates for studying the transport physics of metal/semiconductor hybrids for optoelectronic applications.

CuO nanorods from carrier solvent assisted interfacial reaction processes: An unexpected extraordinary Fe-free photocatalyst in sunlight assisted Fenton-like processes

Abstract CuO nanorods, prepared with a fast and simple one step carrier solvent assisted interfacial process, were found to be an extraordinary Fe-free Fenton-like photocatalyst. CuO nanorods of around 12 nm in diameter and 200–400 nm in length were produced at ambient pressure and room temperature in 30 min. The extraordinary organic pollutant degradation efficiency of these CuO nanorods was demonstrated with photodegradation of Rhodamine B (RhB), one of the most recalcitrant organic pollutants, in a Fenton-like process under illumination of simulated sunlight at 100 mW/cm2. The apparent reaction rate constant reached as high as 0.84 min−1 for treating 50 ppm RhB solutions and was maintained at a decent value of 0.19 min−1 for treating RhB solutions of an extremely high concentration of 500 ppm. A degradation mechanism was proposed to show how chemical and photochemical catalyzations work to realize the extraordinary degradation efficiency of the CuO nanorods. The outstanding photodegradation performances of these CuO nanorods for treating high concentration RhB solutions prove their practical applicability for treating industrial effluents using sunlight assisted Fenton-like processes.

Fabrication and Photoelectrochemical Properties of a Cu2O/CuO Heterojunction Photoelectrode for Hydrogen Production from Solar Water Splitting

We report on the fabrication and characterization of a novel Cu2O/CuO heterojunction structure with CuO nanorods embedded in Cu2O thin film as an efficient photocathode for photoelectrochemical (PEC) solar water splitting. A CuO nanorod array was first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method; then, a Cu2O thin film was electrodeposited onto the CuO nanorod array to form an oxide semiconductor heterostructure. The crystalline phases and morphologies of the heterojunction materials were examined using X-ray diffraction and scanning electron microscopy, as well as Raman scattering. The PEC properties of the fabricated Cu2O/CuO heterojunction photocathode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the Cu2O/CuO photocathode was found to exhibit negligible dark current and high photocurrent density, e.g. −1.05 mA/cm2 at −0.6 V vs. Hg/HgCl2 in 1 mM Na2SO4 electrolyte, revealing the effective operation of the oxide heterostructure. The photocurrent conversion efficiency of the Cu2O/CuO photocathode was estimated to be 1.27% at −0.6 V vs. Hg/HgCl2. Moreover, the PEC current density versus time (J-T) profile measured at −0.5 V vs. Hg/HgCl2 on the Cu2O/CuO photocathode indicated a 3-fold increase in the photocurrent density compared to that of a simple Cu2O thin film photocathode. The improved PEC performance was attributed to a certain synergistic effect of the bilayer heterostructure on the light absorption and electron-hole recombination processes.

Oxygen vacancy-induced red light emission from flexible inorganic micropatterned p-CuO/n-ZnO heterojunction light-emitting diode

Fully inorganic flexible light-emitting diodes (LEDs) were demonstrated by using CuO nanorods (NRs) and ZnO NRs as the hole and electron transport materials, respectively. The heterojunctions were fabricated inside 5 μm square patterns in order to achieve better flexibility. The current-voltage characteristic of the heterojunction revealed a typical p-n diode nature with an on-off ratio of 8.6 × 102 at 4 V, a turn-on voltage of 2.8 V, and a stable current flow at different voltage stress. The electroluminescence spectra from the LED at different forward bias exhibited eminent peak at around 710 nm corresponding to red light, which was in accordance with the deep-level emission of photoluminescence spectra of ZnO NRs. The Zn 2p and O 1s narrow-scan X-ray photoelectron spectra revealed that the deep levels are related to oxygen vacancies. The devices showed significant stability during bending test and continued to emit light beyond 1000 cycles of dynamic bending at a radius of curvature of 5 mm.

Synthesis and photoelectrochemical properties of a novel CuO/ZnO nanorod photocathode for solar hydrogen generation

Here, we present a facile synthesis method and photoelectrochemical characterizations of a p-type CuO-nanorod array photoelectrode with ZnO nanorod branches. Vertically-aligned CuO nanorods were synthesized by using direct oxidation of metallic Cu nanorods grown on a Cu substrate by using a facile template-assisted electrodeposition method. The formed CuONR/ZnONB hierarchically-structured photoelectrode exhibited remarkable photoelectrodechemical performance and outstanding stability compared to the CuO NR photoelectrode without ZnO NR branches. Morphological, optical and electrochemical characterizations were carried out in order to examine the effects of ZnO nanorod branches on the stability and the overall electrochemical performance of the electrode.

In situ growth of ultrashort rice-like CuO nanorods supported on reduced graphene oxide nanosheets and their lithium storage performance

A facile refluxing strategy in aqueous solution was engaged to synthesize ultrashort rice-like CuO nanorods/reduced graphene oxide (CuO-NRs/rGO) composite. The result of the high-resolution transmission electron microscopy shows that the as-synthesized rice-like CuO nanorods have a uniform size of about 8 nm in width and 28 nm in length and are homogenously dispersed on rGO nanosheets. The CuO nanorods are uniformly dispersed and immobilized by the graphene nanosheets reduced from GO. The resultant CuO-NRs/rGO composite as anode material for lithium-ion batteries displays better electrochemical properties than those of pure CuO-NRs and rGO nanosheets. The high reversible capacity and good stability can be ascribed to the presence of rGO nanosheets.

Palladium networks decorated by cuprous oxide for remarkably enhanced electrocatalytic activity of methanol oxidation reaction with high CO-tolerance

Abstract The CuO nanorods (NRs) are prepared with the help of inositol hexakisphosphate which serves as a binding agent and stabilizer. We have successfully fabricated Cu 2 O-decorated palladium networks (Cu 2 O/Pd Networks) by using such CuO NRs as reaction beds. Transmission electron microscopy images show that Cu 2 O/Pd network is composed of small and irregular fused nanoparticles with an average size of about 10 nm. Electrochemical results depict that the as-synthesized catalyst exhibits 2-fold higher activity for methanol oxidation than the commercially available 20% Pd/C catalyst and Pd black catalyst. Furthermore, CO-tolerance is also remarkably enhanced due to the presence of Cu 2 O. Such highly active, low-cost, and superiorly CO-tolerant catalysts of Cu 2 O/Pd Networks will open up a new avenue for direct methanol fuel cells.