Catalytic Activity Of Copper Nanoparticles Research Articles

Fabrication and Characterization of Cu Nanoparticles Dispersed on ZnAl-Layered Double Hydroxide Nanocatalysts for the Oxidation of Cyclohexane.

In the chemical industry, designing high-performance catalysts for the oxidation of cyclohexane into value-added products such as cyclohexanol and cyclohexanone (the combination is known as KA oil) is critical. The catalytic activity of copper nanoparticles supported on layered double hydroxide (LDH) for the liquid phase oxidation of cyclohexane was examined in this study. In this work, we have developed Cu nanoparticles supported on layered double hydroxide nanocatalysts, abbreviated as CuNPs@LDH, by the chemical reduction approach. Various physical methods were used to characterize the resulting material, including ICP-AES, XRD, FTIR, SEM, EDX, HRTEM, and BET surface area. The catalytic activity of copper nanoparticles supported on LDH was examined for the liquid phase oxidation of cyclohexane with tert-butyl hydroperoxide. CuNPs@LDH nanocatalysts with an excellent 52.3% conversion of cyclohexane with 97.2% selectivity of KA oil was obtained after 6 h at 353 K. The hot filtration test further indicated that CuNPs@LDH was a heterogeneous catalyst that could be recycled at least six times without suffering a substantial reduction in its catalytic activity.

Enhanced catalytic activity of copper nanoparticles electrochemically Co-deposited with cadmium towards the electroreduction of nitrate

• Size of polyhedral Cu nanoparticles (NPs) shrank once Cd was introduced. • Size shrink was accompanied with evident activity promotion to nitrate reduction. • Mismatch between the two metal lattices might cause the size shrink. • Rate determining step for CuNPs and CuCdNPs was probably different. • Size or synergistic (CuCd bimetal) effect needs to be further studied. Polyhedral copper nanoparticles (CuNPs) were potentiostatically electrodeposited upon stainless-steel from a hydrophobic protic amide-type ionic liquid (IL), i.e. protonated-betaine bis((trifluoromethyl)sulfonyl)amide ([Hbet][TFSA]) containing CuO as the precursor. The surface morphologies and electrocatalytic activities of the CuNPs towards nitrate reduction were significantly altered after the co-deposition of cadmium (Cd). The variation of morphology and activity was caused by the significant shrinkage of the particle size as a result of the Cd co-deposition and the synergistic effect of Cu and Cd bimetal. In the galvanostatic electrolysis of nitrate, CuNPs showed a much higher reductive overpotential in comparison with CuCdNPs. It might be caused by a kinetic hindrance for the CuNPs in the rate-determining step of nitrate reduction ( i.e. formation of nitrite ion NO 2 − ). CuCdNPs, however, exhibited the robust and stable activity in which the rate-determining step was determined as a two-electron transfer reaction in accordance with the Tafel slope.

Enzyme-free colorimetric nanosensor for the rapid detection of lactic acid in food quality analysis

Lactic acid is an essential organic chemical in food, clinical, chemical, and bioprocessing industries. We are reporting for the first time, a rapid and facile enzyme-free colorimetric sensor for the detection of lactic acid (LA) in food samples using nitrophenol ( p -NP) added copper nanoparticles (CuNPs). The responses of p -NP (5 mmol/L) to lactic acid in the presence of CuNPs were reported by analysing the UV-VIS absorption spectra in an aqueous solution. CuNPs were synthesized by the chemical reduction method and were identified to be in the Cubic phase using XRD analysis. The sample characterization studies were performed using the SEM, UV for obtaining good optical and selective lactic acid-sensing properties. The sensing mechanism is due to the aggregation responses of CuNPs conjugated p -NP in the presence of lactic acid as seen in the UV-VIS absorption spectra shift studied in an aqueous solution. The absorption spectrum of p -NP exhibited one intense band at 402 nm in the presence of CuNPs. Although the addition of lactic acid may cause π –π* transitions led to a hypsochromic shift (blue shift) with a subtle decrease in the wavelength from 402 to 315 nm, the solution underwent from being colored (greenish-yellow) to colorless. The stoichiometric ratio of a binding event is explained using Job's plot. The naked eye colorimetric response of the sensor-enabled detection limit of lactic acid to 0.33 mM. The sensor studies were compared with standard LC-MS/MS revealing a good recovery (95%) in food samples. This method is facile and alternate to the current high-cost techniques and enzymatic sensors. Schematic illustration of colorimetric sensor- CuNPs assisted catalytic reduction of p -nitrophenol (colored) to p -aminophenol (colorless) with the exposure of lactic acid. • Nonenzymatic colorimetric nanosensor for lactic acid detection. • The visual detection of trace amounts of lactic acid as low as 0.33 mM. • Sensor is based on the catalytic activity of copper nanoparticles. • Application of developed sensor for real time food sample analysis.

Green synthesis and catalytic activity of copper nanoparticles supported on TiO2 as a highly active and recyclable catalyst for the reduction of nitro-compounds and degradation of organic dyes

Green synthesis and catalytic activity of copper nanoparticles supported on TiO2 as a highly active and recyclable catalyst for the reduction of nitro-compounds and degradation of organic dyes

Enhancement of both optical and catalytic activity of copper-decorated porous silicon micro-particles

To the best of our knowledge, this study is the first to investigate the effect of chemical vapour etching (CVE) combined with copper decoration on both the optical and catalytic activities of silicon micro-particles (SiμPs). After exposure to acid vapours emanating from a hot solution of hydrogen fluoride/nitric acid (HF/HNO3), scanning electron microscope images of the treated powder show the formation of a porous, sponge-like structure on the sidewalls of SiμPs. Fourier transmission infra-red analysis shows the appearance of hydride bonds related to the formation of the porous structure. X-ray diffraction measurements and Raman spectroscopy show the good crystallinity of the samples. The strong photoluminescence properties of the obtained porous SiμPs (pSiμPs) reveal that the vapour etching process generated silicon nanocrystals within these particles. In this work, we have investigated the catalytic activity of copper nanoparticles (CuNPs) loaded on the surface of pSiμPs, in order to reduce the toxic compound 4-nitrophenol to 4-aminophenol. The results show excellent catalytic performance in very short times (less than 1 min).

Computational screening of M/Cu core/shell nanoparticles and their applications for the electro-chemical reduction of CO2 and CO.

To improve the catalytic activity of copper nanoparticles (Cu NPs) in the electro-chemical catalysis of the CO2 reduction reactions (CO2RRs), the formation and use of core/shell nanoparticles (CSNPs) with Cu as the shell composite may be an effective way. Using Cu79 NP as the representative, we performed computational screening and confirmed four Mx@Cu79-x CSNPs that can stably exist. Then, the catalytic performance of the screened CSNPs was tested through first-principles calculations. The free energy profiles indicate that Fe19@Cu60 is more desirable for CO2RR catalysis due to its high selectivity for CO rather than HCOOH at a low potential. Moreover, when it electro-catalyzes CO2 into CH4, the Fe19@Cu60 CSNP exhibits much lower limiting potential (-0.58 V) compared with pure Cu79 NP (-0.86 V) or the Cu (211) surface (-0.70 V). Taking the cost into consideration, the Fe19@Cu60 CSNP is highly recommended as a promising electro-catalyst for CO2RRs. In addition, when CO is taken as the initial reactant to be reduced, all the screened CSNPs exhibit lower limiting potentials than Cu79 NP. From the view of material design, the significant weakening of CO binding originating from the change in the d-band center could be the reason why the formation of a core/shell structure will enhance the catalytic performance of Cu NPs in CO reduction.

Green Synthesis of Copper Nanoparticles: Evaluation of Catalytic and Antibacterial Activity

The objective of present study is to synthesize copper nanoparticles from Vitex negundo Linn., root bark extract as reducing and stabilizing agents. The synthesized nanoparticles were characterized by using UV-visible spectrophotometer, X-ray diffraction, FTIR, SEM and EDX. The results were shown that copper nanoparticles exhibited UV-visible absorption peak at around 550 nm. The XRD study confirmed that nanoparticles are crystalline in nature. In addition to these, FTIR was also used to analyze the various functional groups stabilized and protected the copper nanoparticles. The SEM results revealed that the copper nanoparticles are spherical, cubic and hexagonal in shape and having the particle size ranging from 40 to 60 nm. Catalytic activity of copper nanoparticles were studied in the Huisgen [3+2] cycloaddition of azides and alkynes to obtain 1,4-disubstituted 1,2,3-triazole at room temperature. Antibacterial profile revealed that the biopotent copper nanoparticles exhibited moderate to good activity against bacterial strains.

Novel 3D copper nanoparticles/chitosan/nanoporous alumina (CCSA) membranes with catalytic activity. Characterization and performance in the reduction of methylene blue

Herein, we report the surface modification of H2O2-treated nanoporous alumina (anodic aluminum oxide, AAO) membranes with chitosan (CS) by a solution casting method. Later, copper nanoparticles were incorporated into this CS-AAO membrane by immersion in an aqueous solution of a copper salt precursor and subsequent reduction using NaBH4. The IR spectra and energy dispersive X-ray spectroscopy (EDS) analyses helped to confirm the presence of CS and copper nanoparticles both on the surface and inside the nanochannels of this AAO membrane (denoted CCSA). Notable differences in the surface energy, surface topography and morphology were observed between the CS-AAO and CCSA membranes. The catalytic performance of the CCSA membrane was tested in the reduction of methylene blue (MB).Our findings revealed that this system adequately combines the attractive properties of supporting of the AAO membranes, ion retention by CS and the catalytic activity of copper nanoparticles into a tridimensional array. Finally, the recyclability of the CCSA membrane was also assessed. The results showed that the performance of this membrane was not dramatically affected after four cycles of use.

Kinetic and Thermodynamic Specific Features of Hydrogenation of Hexene-1, Heptene-1, and Cyclohexene on Catalyst Containing Copper Nanoparticles

Kinetics of hydrogenation of hexene-1, heptene-1, and cyclohexene on copper nanoparticles was studied. To examine the thermodynamic specific features, the entropy of formation of an activated complex, rate constants, and conversion were calculated. A conclusion that the key role is played by the entropy factor in the formation of the activated complex is made on the basis of the data obtained. The similarity between the mechanisms by which activated complexes are formed in the hydrogenation of hexene-1, heptene-1, and cyclohexene and in that of hexyne-1, hexadiene-1,5, and benzene with the use of nickel nanoparticles was confirmed. The results obtained enable a conclusion about the high catalytic activity of copper nanoparticles in reactions of hydrogenation of unsaturated hydrocarbons in the temperature range 140–200°C at a pressure of 2 atm.

Microwave‐assisted facile synthesis of propargylamine library by robust nitro functionalized cross‐linked polystyrene resin supported Cu NPs

AbstractIn the present investigation, we study catalytic activity of copper nanoparticles stabilized onto a nitro functionalized polystyrene resin (Cu NPs@ Nitro‐Resin). The size of stabilized copper nanoparticles was found between 3 and 9 nm. This work reports a cost‐effective and sustainable protocol for the synthesis of propargylamines. Herein, we have developed microwave‐assisted synthesis of propargylamine from 3 components coupling of aldehyde, alkynes, and amines (A3 coupling) in truly heterogeneous catalytic system. Reaction parameters, such as solvent, catalyst concentration reaction time, and recyclability, were investigated, and reaction conditions were optimized. The present method has advantages such as environmentally benign, ease to handle, short reaction time (≈25 min), excellent yields (98%), low E‐factor (0.15), and high atom economy (94%).

Nitro resin supported copper nanoparticles: An effective heterogeneous catalyst for C[sbnd]N cross coupling and oxidative C[sbnd]C homocoupling

In the present study, we investigate the synthesis and catalytic activity of copper nanoparticles (CuNPs) stabilized onto a novel nitro functionalized polystyrene resin. The deposited nanoparticles were characterized by various analytical techniques and TEM images, revealed uniformly distributed copper nanoparticles of sizes 3–9nm. We effectively used the resin impregnated CuNPs for CN coupling of various aromatic amines with aryl halides and for the oxidative CC homocoupling of phenyacetylene. Further, recycling of the catalyst, leaching of metal ions and post reaction changes in the support were studied and it was concluded that the support acts as oxidant during the homocoupling of phenyl acetylene which is oxidative by nature.

ChemInform Abstract: Copper Nanoparticles on Charcoal: An Effective Nanocatalyst for the Synthesis of Enol Carbamates and Amides via an Oxidative Coupling Route.

Abstract The catalytic activity of copper nanoparticles on charcoal (Cu/C) was investigated as an environmentally friendly heterogeneous catalyst for the synthesis of enol carbamates and amides via the oxidative coupling of N,N-dialkyl formamides with 1,3-dicarbonyl compounds and aromatic aldehydes with amine hydrochloride salts, respectively. Various enol carbamates and amides were synthesized in moderate to good yields using this method. Moreover, the catalyst could be recovered and subsequently reused in further reactions.

Copper nanoparticles on charcoal: an effective nanocatalyst for the synthesis of enol carbamates and amides via an oxidative coupling route

The catalytic activity of copper nanoparticles on charcoal (Cu/C) was investigated as an environmentally friendly heterogeneous catalyst for the synthesis of enol carbamates and amides via the oxidative coupling of N,N-dialkyl formamides with 1,3-dicarbonyl compounds and aromatic aldehydes with amine hydrochloride salts, respectively. Various enol carbamates and amides were synthesized in moderate to good yields using this method. Moreover, the catalyst could be recovered and subsequently reused in further reactions.

Investigation of the catalytic activity of copper nanoparticles sintered with polycarbonate in benzene hydrogenation

The catalytic activity of copper nanoparticles in benzene hydrogenation is studied. Rate constants at different temperatures and activation energies are calculated.

Electro Oxidation of Methanol on Copper Nanoparticles Supported Poly (O- Amino Phenol) Nanotubes

In this article, the electrochemical synthesis and the characterization of Cu nanoparticles dispersed poly (o-aminophenol) (POAP) nanotube electrode is reported. The morphology of the electrode was characterized by scanning electron microscopy (SEM). Catalytic activity and stability for the oxidation of methanol were studied by using cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were performed. The results show that poly (o-aminophenol) nanotubes electrodes significantly enhance the catalytic activity of copper nanoparticles for oxidation of methanol. The results obtained affirm that the dispersion of the copper particles is connected with catalytic response to a higher activity. The nanotubular morphology of poly (o-aminophenol) helps in the effective dispersion of Cu particles facilitating the easier access of methanol to the catalytic sites. The poly (o-aminophenol) nanotubes modified with copper nanoparticles cause a great increase in electroactivity and the electro-catalytic oxidation of methanol.

Chemical and catalytic activity of copper nanoparticles prepared via metal vapor synthesis

Nanocrystalline particles of copper have been prepared using the solvated metal atom dispersion (SMAD) technique. Their chemical and catalytic reactivity have been tested in the Ullman reaction (aryl homocoupling) and the hydrogenation of CO2 to form CH3OH. The powders obtained from different solvents have surface areas of 24–30 m2/g, particle sizes of 20–45 nm, and crystallite sizes of 8–12 nm. The order of activity found toward the aryl homocoupling reaction is Cu*/toluene > Cu*/THF > Cu*/pentane > Cu*/diglyme, with a maximum biphenyl yield of 90% at 150 °C after 6 h for the Cu*/toluene sample. For the CO2 to CH3OH reaction, a maximum conversion of 80% was obtained for the Cu*/pentane/NC-ZnO sample. In general, the Cu*/nanocrystalline (NC)-ZnO samples show a larger conversion of CO2 to methanol at 450 °C compared with NC-ZnO and NC-ZnO/CuO.