Morphology Of Cu Nanoparticles Research Articles

A DFT-based FD-KMC Simulation for Electrodeposition of Copper Nanoparticles on Carbon Electrode Surface

Electrodeposition is often used to load catalysts onto electrode surfaces to enhance their electrochemical activity, thereby improving the performance of redox flow batteries. The kinetic Monte Carlo (KMC) method was used to successfully simulate the nucleation and growth of nanoparticles during the electrodeposition process. However, the reliability of KMC simulation results is closely related to the atomic kinetic parameters derived from quantum-scale calculations. Meanwhile, the electrochemical reaction behaviors during electrodeposition rely on the mass transport of electroactive ions near the electrode surface. To address these issues, density functional theory (DFT) was introduced to obtain the energy barriers required in the calculation of KMC. Simultaneously, the finite difference (FD) method was integrated into the KMC algorithm to provide the transient concentration distribution of the diffusion layer near the electrode surface. This DFT-based FD-KMC method was used to simulate the early stage of electrodeposition of copper (Cu) nanoparticles on carbon electrode surfaces and investigate the effects of bulk concentration and applied potential on the characteristics of deposition morphology of Cu nanoparticles. Additionally, carbon electrode surfaces with different defect site numbers were generated to reveal the influence of surface defect sites on the morphology of the deposited Cu nanoparticles during electrodeposition process.

Synthesis of Colloidal Copper (Cu) Nanoparticles by Pulse Laser Ablation Method (Nd:YAG 1064 nm) in Deionized Water

Copper nanoparticles are usually used for various fields, such as medical, energy, environmental, and others. Copper nanoparticles were successfully synthesized in deionized water (DIW) using the 1064 nm ND:YAG pulse laser ablation method at 85 mJ energy. The resulting colloidal nanoparticles are greenish in color. This study investigates the use of DIW liquid medium that can survive one day after being synthesized or changed. The result is that there is a change in the colloidal photo of copper (Cu) nanoparticles shortly after being synthesized and one day after being synthesized. There is a change in color to become clearer after the colloid is left alone for one day. Not only did the colloid photo change, but the absorbance of the UV-Vis testing of the Cu nanoparticle colloid also changed. Changes in UV-Vis absorption in colloids immediately after being synthesized and after colloids were left standing for one day decreased from 1.175 to 0.561, and experienced a shift in wavelength from 222.96 nm to 223.07 nm. The morphology of Cu nanoparticles was seen using FESEM with a spherical shape. The average size distribution of Cu nanoparticles is about 56.7 nm.

Investigation on M@CuOx/C (M=Ru, Rh, Pd and Pt) catalysts prepared by galvanic reduction for hydrogen evolution from ammonia borane

The development of a cost-effective catalyst for hydrogen evolution from ammonia borane is of importance for the application of AB as a hydrogen storage material. In this manuscript, a series of noble metal catalysts M@CuOx/C (M = Ru, Rh, Pd, and Pt) are prepared by the galvanic reduction method. The catalysts are characterized by XRD, TEM, EDS mappings and lines scanning, XPS, HAADF-STEM, and ICP-OES. The noble metal is highly dispersed on the surface of Cu nanoparticles. The morphology of Cu nanoparticles changed according to different metals after the introduction of noble metal and there has an interaction between the noble metal and Cu. The M@CuOx/C is used for the hydrolysis of AB. For the same metal catalyst, the activity of M@CuOx/C is increased by about 3–7 times than the corresponding M/C at 298 K. The Rh shows the highest TOF and lowest activation energy among the four noble metals.

Electrochemical nitrate reduction as affected by the crystal morphology and facet of copper nanoparticles supported on nickel foam electrodes (Cu/Ni)

Cu/Ni composite electrodes were prepared and studied for the electrochemical reduction of nitrate in aqueous solutions. Electrodeless plating technique, with tartrate as chelatant and formaldehyde as reducing agent, enabled the in-situ incorporation of Cu nanoparticles into the open-pore structured Ni foam to form Cu-Ni composite electrodes. X-ray diffractometer (XRD) and scanning electron microscopy (SEM) revealed that the crystal facet and grain morphology of Cu nanoparticles was closely controlled by the plating time and played a significant role in nitrate reduction and nitrogen selectivity. Cyclic voltammetry provided information on the electron transfer between surface nitrogen species and Cu/Ni electrodes. Electrochemical nitrate reduction was initiated at the onset potential of Cu(0)/Cu(I) redox reaction over a potential window of −0.6 V to −1.2 V. The preferential Cu{1 1 1} facet orientation improved the electron transfer process. Batch kinetics studies at constant current and potential showed that specific adsorption of nitrate and nitrite on the Cu{1 1 1} facet was critical to efficient electrochemical nitrate reduction. Moreover, the conversion of nitrogenous byproduct was potential-dependent. Results showed that N2 selectivity was high (55.6%) at low overpotential (i.e., ⩾−0.6 V vs. Hg/HgO. At high overpotential (i.e, <−0.6 V) there was complete of NO3− reduction with NH4+ as major byproduct.

Copper nanoparticles anchored onto boron-doped graphene nanosheets for use as a high performance asymmetric solid-state supercapacitor.

There is a high demand for high energy and power density in the field of energy storage devices. To rectify these limitations, a novel asymmetric solid-state supercapacitor (ASSC) was designed and fabricated using a copper anchored boron doped graphene nanosheet (CuBG) as a negative electrode and reduced graphene nanoplatelets as a positive electrode with H2SO4/PVA as the quasi-solid electrolyte. The CuBG was prepared using a two step hydrothermal process followed by pyrolysis at different temperatures using chemical vapour deposition (CVD), using copper sulphate (CuSO4) and boron-trioxide (B2O3) as precursors, for doping in graphene oxide. Owing to the remarkable structure and morphology of Cu nanoparticles on nanosheets of boron intercalated with graphene oxide, the nanosheets exhibit a high specific capacitance of 483 Fg−1 at 1 Ag−1 with a capacitance retention of 96% after 5000 cycles, respectively, in a two-electrode system. In addition, the designed and fabricated solid state ASSC device of rGO//CuBG exhibited a high energy and power density of 132.5 W h kg−1 and 1000 W kg−1, respectively, in a wide potential window of 2.0 V, with an excellent stability, retaining 91% of its initial specific capacitance after 5000 cycles. The electrochemical capacitance of CuBG was also evaluated in a three and two electrode system using a KOH and KOH/PVA solid electrolyte respectively. A specific capacitance of 87.5 Fg−1 was achieved at 1 Ag−1 using the fabricated asymmetric device with a 31.1 W h kg−1 energy density at a corresponding power density of 800 W kg−1 and an 85% capacitance was retained after 5000 cycles. The kinetics of the interfacial charge transport phenomena were analysed using a Nyquist plot of the electrochemical impedance analysis.

Thermal stress induction for improving the absorption of raw cotton fabric and its effect on the morphology of in situ synthesized Cu nano particles

Chemical processes for improving cotton fabric absorption, such as scouring, are costly and not environmentally friendly. This study introduced a novel and eco-friendly method based on thermal shock for this purpose. Greige cotton fabric samples underwent different thermal shock sequences with dry ice and boiling and cooling water. The samples were characterized using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, methylene blue number and Brunauer–Emmett–Teller absorption isotherm were used for specific surface area measurement. A constant-rate-of-extension type tensile testing machine was also used to determine the tensile mechanical properties of the fabrics, and the effect of thermal shock on moisture regain, water absorption time, and amount of wax removal were investigated. Finally, nanoparticles of copper (Cu) were synthesized in situ on both the thermally shocked and greige fabric samples, and the absorption and particle size were compared. The thermally shocked samples showed longitudinal micro cracks, their water absorbency time decreased and their moisture regain increased (up to 14%). After treatment, no significant shrinkage or strength loss was detected. Synthesized Cu nanoparticles without the presence of cotton substrate showed a mean size larger than 825 nm, but particle sizes decreased to 297 and 69 nm in the presence of the greige and the DiH8 cotton fabric samples, respectively. The morphology of Cu nano particles altered from octahedral to spherical and was more homogeneously distributed for thermally shocked sample.

Polymeric nanoparticle of copper(II)-4,4′-dicyanamidobiphenyl ligand: Synthetic, spectral and structural aspect; application to electrochemical sensing of dopamine and ascorbic acid

In this research, new polymer of 4,4′-dicyanamidobiphenyl (bpH2)-Cu(II) complex, [Cu(bp)(H2O)2]n, has been synthesized and characterized by FT-IR, UV–vis spectroscopy and elemental analysis. The spherical morphology of Cu nanoparticles was confirmed by scanning electron microscopy (SEM) image and the transmission electron microscopy (TEM) image showed that the particle size dimensions of Cu nanoparticles were about 80nm. Thermal gravimetric analysis (TGA) results indicated that this polymer was thermally stable. Hence, the prepared polymer was used as a modifier for the electrochemical determination of dopamine (DA) and ascorbic acid (AA). Compared to the bare carbon paste electrode (CPE) and multiwall carbon paste electrode (CNTPE), bpCu modified CPE (bpCu-CPE) exhibits much higher electrocatalytic activities toward the oxidation of dopamine and ascorbic acid with an increase in peak currents and a decrease in oxidation overpotentials. The effects of scan rate, concentration and pH were also studied. Differential pulse voltammetry results show that DA and AA could be detected selectively and sensitively at bpCu-CPE with peak-to-peak separation of 200mV. Relative standard deviations for AA and DA determinations were less than 2.5%, and the linear response ranges of the electrode were 0.05–30.0μmolL−1 for AA and DA, respectively. The calculated detection limits were 0.02 and 0.04μmolL−1 (S/N=3) for AA and DA, respectively. In addition, the presented method was successfully applied for the simultaneous determination of DA and AA in urine and blood samples with reliable recovery.

Preparation of Monodispersed Copper Nanoparticles by an Environmentally Friendly Chemical Reduction

AbstractIn this paper, highly dispersive nanosized copper particles with a mean particle size of less than 6 nm are prepared by an environmentally friendly chemical reduction method. Non‐toxic L‐ascorbic acid acts as both reducing agent and antioxidant in ethylene glycol in the absence of any other capping agent. Transmission electron microscopy (TEM) is used to characterize the size and morphology of Cu nanoparticles. The results of UV‐Vis spectroscopy (UV‐Vis), energy dispersive spectroscopy (EDS) and high resolution TEM (HRTEM) illustrate that the resultant product is pure Cu nanocrystals. The size of Cu nanoparticles is remarkably impacted by the order of reagent addition, and the investigation reveals the reaction procedure of Cu2+ ions and L‐ascorbic acid.