Copper Oxide Nanostructures Research Articles

Melamine assisted large-scale and rapid synthesis of porous copper oxide nanostructures

Melamine assisted large-scale and rapid synthesis of porous copper oxide nanostructures

Oxalic acid-derived combustion synthesis of multifunctional nanostructured copper oxide materials

Oxalic acid-derived combustion synthesis of multifunctional nanostructured copper oxide materials

A deterministic approach to the thermal synthesis and growth of 1D metal oxide nanostructures

The 1D metal oxide nanostructures, including nanowires, are researched for at least two decades. However, the theoretical models on their synthesis and growth mechanisms are still controversial, even for the simplest growth method, namely thermal oxidation of a metallic surface. In this paper, the relevance analysis of the growth conditions reported in the literature is conducted, followed by the developed theoretical model, which was verified by our experiment on copper oxide nanowires. The model quantitatively describes the two most applied hypotheses concerning the single- and bi-crystalline growth of copper oxide nanowires. The numerical simulations reveal the conditions for both obtained mechanisms. It is also established that for the growth of the relatively thick nanowires associated with the single crystals, the internal energy of oxygen molecules determines the mechanism of oxygen adsorption. The energy can be re-distributed at the oxygen attachment, and the molecule can desorb at the account of this energy. Furthermore, the obtained result are also useful for developing the theory on nanowire seed generation, identifying the key control factors and basic mechanisms behind the growth modes, making a step toward a deterministic, highly predictable synthesis of dense 1D copper oxide nanostructures.

Pitch‐Black Nanostructured Copper Oxide as an Alternative to Carbon Black for Autonomous Environments

Light detection and ranging (LiDAR) systems are becoming crucial for measuring the distance and creating a point cloud of the local environment, critical data for artificial intelligence to enable collision‐avoidance mechanisms. However, LiDAR utilizes radiation in the near‐infrared (NIR) region of the electromagnetic spectrum, which is prone to complete absorption by typical dark (such as painted by carbon black) colored objects, leading to loss of timely data points. Till date a very limited number of solutions have been put forward to address this. Herein, nanocrystallites of copper (II) oxide with specific prevalence of crystal facets that create nearly perfect black material at visible wavelengths are proposed. The sharp transition of absorbance near 700 nm wavelength light is attributed to the near‐unity ratio of (−111)/(111) the crystal facets and a crystal size of around 100 Å for the (−111) plane. Although indistinguishable from carbon black and with the same degree of measured blackness (My value 135.5), the nanocrystalline CuO shows 1500% better detectability by LiDAR. The study paves the way for the unconstrained use of dark objects in future society and infrastructure, moving a step closer toward fully autonomous operation of vehicles and robots.

Facile and low-cost synthesis of diverse copper oxide nanostructures for solar to thermal energy conversion

Copper oxide (CuO) nanostructures were synthesized through a simple and low-cost wet chemical method using copper nitrate trihydrate as precursor and sodium hydroxide (NaOH) as stabilizing agent. Scanning electron microscopy analysis revealed formation of diverse CuO nanostructures as a consequence of varying the concentration of NaOH in the reaction medium. X-ray diffraction examination disclosed existence of end-centered monoclinic structured CuO as evident from the diffraction peaks observed at 2θ values corresponding to diffraction planes. Existence of cubic phase Cu2O was confirmed by presence of diffraction peak at 2θ value of 61.5°, corresponding to [0 2 2] diffraction plane. Energy-dispersive X-ray spectroscopy analysis proved pristine nature of the CuO nanostructures. UV-Vis-NIR reflectance value of CuO nanostructures prepared using different concentrations of NaOH exhibited reliable solar absorptance values, which were in accordance with their respective reflectance values. Among them, the CuO nanostructure prepared using NaOH concentration of 1.0 M disclosed high solar absorptance and selectivity values of 0.80 and 18.60, respectively.

Benchmarking of oxygen evolution catalysts on porous nickel supports

Summary Active and inexpensive oxygen evolution reaction (OER) electrocatalysts are needed for energy-efficient electrolysis applications. Objective comparison between OER catalysts has been blurred by the use of different supports and methods to evaluate performance. Here, we selected nine highly active transition-metal-based catalysts and described their synthesis, using a porous nickel foam and a new Ni-based dendritic material as the supports. We designed a standardized protocol to characterize and compare the catalysts in terms of structure, activity, density of active sites, and stability. NiFeSe- and CoFeSe-derived oxides showed the highest activities on our dendritic support, with low overpotentials of η100 ≈ 247 mV at 100 mA cm–2 in 1 M KOH. Stability evaluation showed no surface leaching for 8 h of electrolysis. This work highlights the most active anode materials and provides an easy way to increase the geometric current density of a catalyst by tuning the porosity of its support.

An improved non-enzymatic electrochemical sensor amplified with CuO nanostructures for sensitive determination of uric acid

AbstractThis study displays the facile and fluent electrochemical determination of uric acid (UA) through exceptional copper oxide nanostructures (CuO), as an effective sensing probe. The copper oxide nanostructures were fabricated via an aqueous chemical growth method using sodium hydroxide as a reducing agent, which massively hold hydroxide source. Copper oxide nanostructures showed astonishing electrocatalytic behavior in the detection of UA. Different characterization techniques such as XRD, FESEM, and EDS were exploited to determine crystalline nature, morphologies, and elemental composition of synthesized nanostructures. The cyclic voltammetry (CV) was subjected to investigate the electrochemical performance of UA using copper oxide nanostructures modified glassy carbon electrode CuO/GCE. The CV parameters were optimized at a scan rate of 50 mV/s with −0.7 to 0.9 potential range, and the UA response was investigated at 0.4 mV. PBS buffer of pH 7.4 was exploited as a supporting electrolyte. The linear dynamic range for UA was 0.001–351 mM with a very low limit of detection observed as 0.6 µM. The proposed sensor was successfully applied in urine samples for the detection of UA with improved sensitivity and selectivity.

Preparation and photo fenton-like activities of CuO/nanocellulose composite

A combination between the nanostructured photocatalyst and cellulose-based materials promotes a new functionality of cellulose towards the development of new bio-hybrid materials for water treatment and renewable energy applications. In this study, nanocellulose (CNC) was synthesized from sugarcane bagasse (SCB) biomass via formic /peroxyformic acid process treatment and acid hydrolysis at an atmospheric pressure. The resulting CNC of sugarcane bagasse were characterized by crystallinity index, chemical structure and morphology. X-ray diffraction (XRD) analysis revealed that the crystallinity increased with successive treatments. Images generated by TEM showed that CNC was rod-like in morphology, average diameter and length of 10 nm and 410 nm, respectively. The obtained CNC was used as a biotemplate for the synthesis of copper oxide (CuO) nanostructures through in - situ solution casting method. The photo-Fenton catalytic activity was evaluated via the degradation of methylene blue under sunlight irradiation with H2O2 as a oxidizing agent. The methylene blue degradation ratio of CuO/ CNC composite could achieve 98% in 150 min. The addition of H2O2 enhanced photocatalytic activities of the CuO/CNC. H2O2 not only prevented the recombination of charge carriers by accepting the photogenerated electrons and holes effectively but also produced additional OH.

Laser-assisted fabrication and modification of copper and zinc oxide nanostructures in liquids for photovoltaic applications

The work reports on the use of laser ablation and irradiation in acetone and water to prepare copper and zinc oxide nanoparticles (NPs) as potential components for photovoltaic applications. Optical and morphological properties of the products were studied by absorption spectroscopy and transmission and scanning electron microscopy. The possibility of controlled modification of produced NPs and their characteristics by additional laser irradiation was demonstrated. As demonstration of potential of such laser-generated NPs for photovoltaic applications, heterojunction interface was fabricated by spin-coating of p-CuO and n-ZnO thin films onto indium-tin oxide substrate, after which electrical properties of the as-prepared device were evaluated.

Nanostructured jumping-droplet thermal rectifier.

Analogous to an electrical rectifier, a thermal rectifier (TR) can ensure that heat flows in a preferential direction. In this paper, thermal transport nonlinearity is achieved through the development of a phase-change based TR comprising an enclosed vapor chamber having separated nanostructured copper oxide superhydrophobic and superhydrophilic functional surfaces. In the forward direction, heat transfer is facilitated through evaporation on the superhydrophilic surface and self-propelled jumping-droplet condensation on the superhydrophobic surface. In the reverse direction, heat transfer is minimized due to condensate film formation within the superhydrophilic condenser and inability to return the condensed liquid to the superhydrophobic evaporator. We examine the coupled effects of gap size, coolant mass, heat transfer rate, and applied electric field on the thermal performance of the TR. A maximum thermal diodicity, defined as the ratio of forward to reverse heat transfer, of 39 is achieved.

RF Sputter-Deposited Nanostructured CuO Films for Micro-Supercapacitors

Copper oxide is considered as an alternative electrode material for supercapacitors due to its low cost, chemical stability and high theoretical specific capacitance. In the present work, nanostructured copper oxide (CuO) films are prepared by radio-frequency (RF) magnetron sputtering, and the influence of the substrate temperature on the microstructure and supercapacitive properties was studied. The copper oxide films prepared at 350 °C exhibit a predominant (1¯11) orientation corresponding to the monoclinic Cu(II)O phase with a crystallite size of 24 nm. The surface of the film consists of uniformly distributed oval-like grains providing a high surface roughness of 45 nm. The films exhibit an optical bandgap of 1.68 ± 0.01 eV and an electrical conductivity of 0.4 S cm−1 at room temperature. The as-prepared CuO films deliver a discharge specific capacitance of 387 mF cm−2 (375 F g−1) at a current density of 1 mA cm−2 with excellent cyclic capacitance retention of 95% (367 mF cm−2) even after 1000 cycles. Hence, these films are potential electrodes for micro-supercapacitors.

Investigation of Doping Effect on Structural, Optical, Antibacterial and Toxicity Properties of Iron Doped Copper Oxide Nanostructures Prepared By Co-Precipitation Route

In this work, pure copper oxide and Fe-doped copper oxide nanostructures [Cu1-x FexO where 0 ≤ x ≤ 0.08 in steps of 0.02] were synthesized using co-precipitation method. Iron nitrate nano-hydrate and copper nitrate trihydrate as precursors and NaOH was used as precipitating agent. The samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and UV-visible spectroscopy for their structural, morphological and optical properties, respectively. The effect of iron concentration on antibacterial activity and hemolysis were also investigated for Escherichia coli and Bacillus Subtilis. The XRD pattern showed the single-phase monoclinic structure of CuO nanoparticles. The average crystallite size of pure copper oxide was found to be 39 nm whereas average crystallite size of Fe-doped CuO was found to be in the range 39-44 nm. It was observed that average crystallite size was increased with increasing iron concentration in CuO. Scanning electron microscopy analysis showed the spherical like morphology and EDS confirmed the presence of iron and copper with proper composition. UV-vis spectroscopy results showed that band gap was decreased with increasing iron concentration. Samples prepared with higher concentration of iron exhibited high E. coli and B. subtilis antibacterial activity. Low hemolytic is safer to be used in various applications such as drug delivery.

Nano-structured CuO on Silicon Using a Chemical Bath Deposition Process and Sputter Seed Layer

Morphological changes of copper oxide (CuO) nano-structures have been studied in detail for renewable energy and electronic applications. The CuO nano-structures were grown on a silicon substrate via a two-stage process starting with radio frequency sputtering for the seed layer followed by chemical bath deposition. The study was focused on controlling the shape and size of the CuO nano-structures depending on various growth conditions, such as reaction time, growth temperature, and vertical/horizontal orientation of the substrate containing the sputtered-grown seed layer. Structural, optical, crystallographic, and morphological characteristics of the nano-structures were obtained through field-emission scanning electron microscopy, x-ray diffraction crystallographic analysis, and UV–Vis spectroscopy.

Structural, Optical and Antibacterial Efficacy of Pure and Zinc-Doped Copper Oxide against Pathogenic Bacteria.

Copper oxide and Zinc (Zn)-doped Copper oxide nanostructures (CuO-NSs) are successfully synthesized by using a hydrothermal technique. The as-obtained pure and Zn-doped CuO-NSs were tested to study the effect of doping in CuO on structural, optical, and antibacterial properties. The band gap of the nanostructures is calculated by using the Tauc plot. Our results have shown that the band gap of CuO reduces with the addition of Zinc. Optimization of processing conditions and concentration of precursors leads to the formation of pine needles and sea urchin-like nanostructures. The antibacterial properties of obtained Zn-doped CuO-NSs are observed against Gram-negative (Pseudomonas aeruginosa, Klebsiella pneumonia, Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria via the agar well diffusion method. Zn doped s are found to have more effective bacterial resistance than pure CuO. The improved antibacterial activity is attributed to the reactive oxygen species (ROS) generation.

ICMMS-2: Comparative Study on Copper Oxide Nanocrystals Synthesized by Two Precipitation Methods

Copper oxide (CuO) nanostructures have attracted a lot of interest in recent years due to their interesting properties. In this study, preparation CuO nanostructures through the chemical reduction of copper sulfate with acetic acid. In our synthesis route, starch was added and worked both as a size and shape controller. The synthesized nanostructures were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmittance electron microscope (TEM). The average particle diameters were determined by the Debye-Scherrer equation and Analysis by Thermogravimetric analysis (TGA), BET.

Green-synthesized copper oxide nanostructures for potential multifaceted biomedical applications

The novelty of the present work is the in-vitro and in vivo nano-antibitoic combinational therapy along with in vitro anti-cancer and biocompatibility activities of green synthesized CuO NLs.

Green Synthesis of CuO Nanostructures using Syzygium guineense (Willd.) DC Plant Leaf Extract and Their Applications

The medicinal plant, Syzygium guineense (Willd.) DC (Waterberry) mediated green copper oxide nanostructures (SyG-CuO NSs) were successfully synthesized for the first time in Ethiopia. The antibacterial activity of CuO NSs capped by biomolecules of the plant leaf extract has been investigated. The UV-visible, UV-DRS, FT-IR, XRD, TGA-DTA, SEM, EDXA, TEM, HRTEM and SAED techniques were employed to characterize the NSs. The presence of two absorbance maxima, λmax1 and λmax2 at 423 nm and 451 nm, respectively confirms a mixture of copper oxide (Eg=1.93 eV). FTIR spectra confirmed the presence of biomolecules with SyG-CuO NSs. The XRD patterns of NSs confirmed the presence of CuO with high crystallinity. The purity of the NSs was confirmed by SEM-EDAX analysis. In addition, TEM-HRTEM-SAED analysis revealed the d-spacing value of 0.2854 nm which corresponds to CuO (111) lattice fringe. SyG-CuO NSs showed good antibacterial effect against both Gram-positive bacteria, S. aureus (12 mm), and Gram-negative bacteria, E. coli (12 mm), P. aeruginosa (10 mm), and E. aerogenes (12 mm). The bioactive compounds capped around the CuO NPs served the effective role in disrupting the cell wall of bacterial strains. The CV and EIS studies confirmed the better electrochemical properties for SyG-CuO with low charge transfer resistance value of 49 Ω. These CuO NSs exhibited multifunctional applications.

Hollow 1D copper oxide nanostructures with enhanced activity for catalytic reduction and photocatalytic degradation of organic pollutants

Catalytic reduction and photocatalytic degradation are two important methods used for remediation of organic pollutants in waste water streams. Copper oxide is a fascinating material that can exhibit catalytic activity in both reactions. In this study we created various 1D copper oxide nanostructures using thermal oxidation of pre-synthesized copper nanowires. The process yield wire like, rod like and tubular wire like copper oxide nanostructures. The tubular morphology is formed by the classic Kirkendall effect. The BET surface area follows the order copper nanowire precursor > 400 °C annealed sample (tube structure) > 150 °C annealed sample (wire like structure)> 180 °C annealed sample (rod like structure). The efficiency of the synthesized materials in catalytic reduction reaction is tested using para nitrophenol reduction reaction. The visible light photocatalytic activity of the materials is tested using the degradation of methyl orange reaction. The synthesized materials show promising activity in both reactions. Interestingly, the copper oxide nanostructures outperform precursor copper nanowires, which possess the highest surface area, in both reactions. The sample calcined at 400 °C exhibits almost twice the catalytic activity than that of metallic copper in the hydride reduction reaction. The photocatalytic degradation rate exhibited by the same copper oxide nanostructure is 23 times higher than that of copper nanowires. The copper oxide nanostructure prepared in this study show catalytic activity almost an order of magnitude higher than copper oxide nanoparticles reported in literature. Catalytic cycling studies show that the synthesized materials show little reduction in property even after three cycles. The macroscopic wire like morphology, and high catalytic activity in reduction reaction and visible light photoactivity make the synthesized materials multipronged for applications like waste water remediation.

Gas sensor using gold doped copper oxide nanostructured thin films as modified cladding fiber

We investigate the spectral response of nanostructured copper oxides thin film. Gold was doped in two different concentrations (2% and 4%) using the spray method. A novel ammonia gas sensor at various concentrations (0–500 ppm) was fabricated by replacing CuO films with a clad region. In addition, the effect of gold doping on structural, optical, and morphological properties has been demonstrated. The study shows that the spectral intensity increases linearly with ammonia concentration. The 4% Au doped CuO presents higher sensitivity compared with 2% doped and pure copper oxides. Time response characteristics of the sensor are also reported.

Bifunctional Electrocatalyst for Aqueous Type Rechargeable Li-Air Batteries Derived from Copper Chelate Polymer

1. Introduction Lithium-air (Li-O2) batteries have attracted focus of many research groups worldwide due to their higher theoretical gravimetric energy density in comparison to the current Li-ion batteries. With the three times higher energy density, such batteries could power electrical vehicles up to 500 km distance on a single charge. Commercialization of these batteries is hindered by the development of bifunctional catalyst that can efficiently catalyze both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Various metal and oxide nanoparticles have been studied as a catalyst. Recently, metal-organic framework structures have shown good catalytic properties. Here, we propose to use a chelate polymer as the template that provides well-dispersed metal oxides. Chelate polymers are peculiar metal-organic hybrid structures. The most extensively studied chelate polymer is copper dithiooxamide (Cu(dto).1) Herein, a new method is proposed for preparing an efficient bifunctional electrocatalyst well dispersed in a carbon matrix. The method includes in situ electrochemical transformation of Cu(dto) compound into copper oxides in alkaline solutions. 2. Experimental Cu(dto) was synthesized by mixing corresponding aqueous solutions of metal salts and ethanolic solution of dto in 1:1 stoichiometric ratio. The compounds were characterized by powder X-ray diffraction (XRD), SEM-EDX, and cyclic voltammetry (CV). The active material slurry was deposited on the surface of a glassy carbon electrode (GCE) used as a working electrode. The catalytic activities of the electrodes were studied by linear swept voltammetry (LSV) and rotating disk electrode (RDE) methods. All experiments were performed in an aqueous 1M KOH solution, with/without oxygen feeding in a three-electrode glass cell. 3. Results and Discussion Cu(dto) compounds were obtained using several copper precursors. The yields obtained from CuSO4, Cu(NO3)2, Cu(CH3COO)2, and CuCl2 precursors were 100%, 99%, 94%, and 100%, respectively. Upon electrochemical cycling, the compound underwent in-situ decomposition to Cu(I) and Cu(II) resulting in the formation of nanostructured copper oxides dispersed on acetylene black, as shown in Fig.1. In this Cu(dto)-derived (Cu(dto)-DO), copper oxide electrocatalyst, CuO and Cu2O are proposed to be the active catalytic species for OER and ORR, respectively. This catalytic system exhibited superior OER performance, indicated by a low overpotential of 400 mV at 10 mA/cm2 and a small Tafel slope of 81 mV/dec in a nitrogen-saturated 1 M KOH solution. It gives a seven-fold higher current density per gram of the metal with comparison to the best-performing IrO2/C as shown in Figure 2.2) The ORR performance of this catalyst showed an onset potential and a half-wave potential of 0.81 and 0.72 V vs. RHE, respectively, in an oxygen-saturated 1 M KOH. The half-wave potential of this catalyst is comparable with the best-performing Pt/C catalyst.3) The results reveal a new way to produce a highly active noble-metal-free bifunctional catalytic system in a carbon network on a large scale using in-situ electrochemical transformation. This catalytic system has the potential to be applied as the active component of a cathode in aqueous type metal-air batteries. References 1) Abboudi M. et al., Synthesis of d-Transition Metal Sulfides from Amorphous Dithiooxamide Complexes. J. Solid State Chem., 109, 70 (1994).2) R.P. Putra, H. Horino, I.I. Rzeznicka, An Efficient Electrocatalyst for Oxygen Evolution Reaction in Alkaline Solutions Derived from a Copper Chelate Polymer via in situ Electrochemical Transformation, Catalysts, 10, 233 (2020).3) R.P. Putra, Y. Samejima, S. Nakabayashi, H. Horino, I.I. Rzeznicka, Copper-based Electrocatalyst Derived from a Copper Chelate Polymer for Oxygen Reduction Reaction in Alkaline Solutions, Catalysis Today, (2020). Acknowledgements The authors would like to thank Shibaura Institute of Technology and Japan Society for Promotion of Science under the JSPS KAKENHI Grant Number JP 20K05689 for financial supports. Figure 1