Simple Electrochemical Synthesis Research Articles

Simple electrochemical synthesis of cyclic hydroxamic acids by reduction of nitroarenes.

The electrochemical reduction of nitroarenes allows direct access to manifold nitrogen containing heterocycles. This work reports the simple and direct electro-organic synthesis of 18 different examples of 2H,4H-4-hydroxy-1,4-benzoxazin-3-ones in up to 81% yield. The scalability of the method was demonstrated on a gram-scale.

Comparative Spectroscopic Study Revealing Why the CO2 Electroreduction Selectivity Switches from CO to HCOO- at Cu-Sn- and Cu-In-Based Catalysts.

To address the challenge of selectivity toward single products in Cu-catalyzed electrochemical CO2 reduction, one strategy is to incorporate a second metal with the goal of tuning catalytic activity via synergy effects. In particular, catalysts based on Cu modified with post-transition metals (Sn or In) are known to reduce CO2 selectively to either CO or HCOO- depending on their composition. However, it remains unclear exactly which factors induce this switch in reaction pathways and whether these two related bimetal combinations follow similar general structure-activity trends. To investigate these questions systematically, Cu-In and Cu-Sn bimetallic catalysts were synthesized across a range of composition ratios and studied in detail. Compositional and morphological control was achieved via a simple electrochemical synthesis approach. A combination of operando and quasi-in situ spectroscopic techniques, including X-ray photoelectron, X-ray absorption, and Raman spectroscopy, was used to observe the dynamic behaviors of the catalysts' surface structure, composition, speciation, and local environment during CO2 electrolysis. The two systems exhibited similar selectivity dependency on their surface composition. Cu-rich catalysts produce mainly CO, while Cu-poor catalysts were found to mainly produce HCOO-. Despite these similarities, the speciation of Sn and In at the surface differed from each other and was found to be strongly dependent on the applied potential and the catalyst composition. For Cu-rich compositions optimized for CO production (Cu85In15 and Cu85Sn15), indium was present predominantly in the reduced metallic form (In0), whereas tin mainly existed as an oxidized species (Sn2/4+). Meanwhile, for the HCOO--selective compositions (Cu25In75 and Cu40Sn60), the indium exclusively exhibited In0 regardless of the applied potential, while the tin was reduced to metallic (Sn0) only at the most negative applied potential, which corresponds to the best HCOO- selectivity. Furthermore, while Cu40Sn60 enhances HCOO- selectivity by inhibiting H2 evolution, Cu25In75 improves the HCOO- selectivity at the expense of CO production. Due to these differences, we contend that identical mechanisms cannot be used to explain the behavior of these two bimetallic systems (Cu-In and Cu-Sn). Operando surface-enhanced Raman spectroscopy measurements provide direct evidence of the local alkalization and its impact on the dynamic transformation of oxidized Cu surface species (Cu2O/CuO) into a mixture of Cu(OH)2 and basic Cu carbonates [Cux(OH)y(CO3)y] rather than metallic Cu under CO2 electrolysis. This study provides unique insights into the origin of the switch in selectivity between CO and HCOO- pathways at Cu bimetallic catalysts and the nature of surface-active sites and key intermediates for both pathways.

Simple Electrochemical Synthesis of Polyethylenimine-Encapsulated Ag Nanoparticles from Solid AgCl Applied in Catalytic Reduction of H2O2

We report a simple and environmentally friendly synthesis of polyethylenimine (PEI)-encapsulated Ag nanoparticles (AgNPs) by a direct electroreduction of solid AgCl. The AgNPs, characterized by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDS), revealed that AgNPs diameters (100–500 nm) depended on the loading of the AgCl precursor. Using cyclic voltammetry (CV), it was confirmed that the AgNPs had a catalytic effect on the electrochemical reduction of H2O2. The obtained AgNPs were subsequently used to construct an electrochemical H2O2 sensor exhibiting a low detection limit (1.66 μM) and a wide linear response range, with real-life tests indicating an insensitivity to common interferents and confirming the potential use of the developed technique in diverse applications.

Efficient inhibition of Salmonella on chestnuts via Fe3C/N-C bacteriostatic suspension prepared by electrochemical method

Chestnuts are susceptible to contamination during collection and storage by Salmonella, which are one of the most important foodborne pathogens. In this paper, an efficient bacteriostatic agent of Fe3C/N-C nanomaterial with good aqueous dispersibility was prepared through the simple electrochemical synthesis strategy. The inhibitory effect of Fe3C/N-C solution on Salmonella enterica subsp. enterica was studied by inhibition zone method, and blue-fluorescent observation of living cells, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and detection of bacterial genomic DNA integration. Results showed that Fe3C/N-C could inhibit Salmonella by injuring both the surface morphology and internal genetic material of Salmonella. Chestnuts contaminated by Salmonella were treated with a 10-fold dilution of the original Fe3C/N-C suspension showed an obvious decreased number of bacteria, while a 5-fold dilution of the same suspension had no toxic to L929 cells. The results indicted a good application prospect in protecting chestnuts from contamination of Salmonella.

High Purity Graphene Oxide Using Electrochemical Synthesis and Its Application

AbstractIn order to fabricate a highly efficient super capacitor, a noble material, graphene oxide (GO), is synthesized by simple electrochemical synthesis method. The chosen source material is an ordinary graphite rod extracted from Nippo battery. Raman spectroscopy as well as Fourier transform infrared spectroscopy affirms the formation of highly pure GO. The super capacitor is fabricated with prepared graphene oxide based electrodes and ionic liquid as electrolyte and tissue paper as separator. The prepared cell shows promising results, a high capacitance value of 78.82 F g−1 at 20 mV s−1 scan rate. The prepared cell is also tested after 30 days in order to determine its stability and performance.

Mixed Copper States in Anodized Cu Electrocatalyst for Stable and Selective Ethylene Production from CO2 Reduction.

Oxygen-Cu (O-Cu) combination catalysts have recently achieved highly improved selectivity for ethylene production from the electrochemical CO2 reduction reaction (CO2RR). In this study, we developed anodized copper (AN-Cu) Cu(OH)2 catalysts by a simple electrochemical synthesis method and achieved ∼40% Faradaic efficiency for ethylene production, and high stability over 40 h. Notably, the initial reduction conditions applied to AN-Cu were critical to achieving selective and stable ethylene production activity from the CO2RR, as the initial reduction condition affects the structures and chemical states, crucial for highly selective and stable ethylene production over methane. A highly negative reduction potential produced a catalyst maintaining long-term stability for the selective production of ethylene over methane, and a small amount of Cu(OH)2 was still observed on the catalyst surface. Meanwhile, when a mild reduction condition was applied to the AN-Cu, the Cu(OH)2 crystal structure and mixed states disappeared on the catalyst, becoming more favorable to methane production after few hours. These results show the selectivity of ethylene to methane in O-Cu combination catalysts is influenced by the electrochemical reduction environment related to the mixed valences. This will provide new strategies to improve durability of O-Cu combination catalysts for C-C coupling products from electrochemical CO2 conversion.

Ultra-long life of TiO2 nanotube array microelectrode for Li-ion microbatteries

It is believed that, as the micropower, lithium ion microbatteries will come into use in implantable medical devices, such as heart pacemaker and neurostimulator. A simple electrochemical synthesis method has been used to prepare TiO2 nanotube array that is expected to be used as the microelectrode in Li-ion microbatteries. The SEM measurements showed that the diameter of the nanotube is in a range of 0.10~0.13 μm; the thickness of the tube wall is about 20~40 nm, and the length of the tube is evaluated to be about 1.47 μm. The charging-discharging measurements have showed us its ultra-long cycle life, i.e., about 6000 cycles; at same time, the discharge capacity of more than 15 μAh/cm2/μm has been remained. It is believed that the nanotube array is a promising candidate for microbattery electrode.

A novel non-enzymatic glucose sensor based on melamine supported CuO nanoflakes modified electrode

In the present work, we describe a simple electrochemical synthesis of CuO nanoflakes (CuO-NFs) using Cu-melamine complex. The as-prepared CuO nanoflakes was characterized by different physicochemical methods such as high-resolution scanning electron microscopy, elemental analysis and elemental mapping. The effect of different potential cycling towards the morphology of CuO-NFs was studied and discussed. Furthermore, CuO-NFs modified electrode was used as an electrocatalyst for oxidation of glucose in 0.1 M NaOH, and the observed electrochemical oxidation current of glucose was higher than CuNPs modified electrode. Amperometric i-t method was used for the determination of glucose using CuO-NFs modified electrode. Under optimal conditions, the amperometric i-t response of the sensor was linear over the glucose concentrations ranging from 1.0 µM to 1.445 mM with the detection limit of 0.35 µM. In addition, the selectivity of the sensor was tested in the presence of different potentially interfering compounds. The practicality of the sensor was also evaluated in human serum samples and shows acceptable recovery of glucose.

A Simple Electrochemical Synthesis and Characterization of Colloidal Silver Nanoparticles

A Simple Electrochemical Synthesis and Characterization of Colloidal Silver Nanoparticles

Simple Electrochemical Synthesis of Cuprous Oxide Nanoparticles and Their Application as a Non-Enzymatic Glucose Sensor

Simple, additive-free nanosynthesis using environmentally benign processes and chemicals has attracted considerable attention in recent times. Cuprous oxide nanoparticles were electrochemically deposited using a simple aqueous electrolyte solution at room-temperature in the presence of air, showing a green, template-less one-step method of electrochemical synthesis. The size and distribution of the particles can be controlled by varying the concentration of sulfuric acid electrolyte. Time of deposition can be controlled to create a uniformly deposited layer of nanoparticles. Deposition potential shows only moderate influence on the size of nanoparticles. Furthermore, it was shown that Cu2O nanoparticles can be effectively used for the fabrication of a low-cost, efficient non-enzymatic glucose sensor. Sensor shows excellent electrocatalytic activity for the electrooxidation of glucose with high sensitivity (507 μA/mMcm2) over a detection range of 100 μM to 2.5 mM. It exhibits good reproducibility and stability with a quick response time (<5 s) and good limit of detection (26 μM) for glucose.

Simple electrochemical synthesis of an Au–Ag–Cu trimetallic nanodendrite and its use as a SERS substrate

An Au–Ag–Cu trimetallic nanodendrite was constructed by simple electrochemical methods and was evaluated as a surface enhanced Raman scattering (SERS) substrate.

Morphologically controlled electrodeposition of fern shaped Bi2Te3 thin films for photoelectrochemical performance

Abstract Bismuth telluride (Bi2Te3) thin films have been proved to be important materials for thermoelectric application. Rapid development of photovoltaic materials has raised new hopes due to directly converting sun light to electricity. We report here a simple electrochemical synthesis route for the preparation of well-defined Bi2Te3 nanostructures for photoelectrochemical solar cell application. Classification of crystal structure, surface morphology and elemental composition of resulting deposits were methodically characterized by X-ray diffraction (XRD) pattern, Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and its photoelectrochemical performance (PEC). The potential range and electrochemical reactions relevant to the growth of Bi2Te3 thin films were studied by cyclic voltammetry (CV). Furthermore, the influence of deposition variables such as applied deposition potential and effect of different surfactants (cationic, anionic and non-ionic) on morphology, crystal orientation associated with the film growth and photoelectrochemical performance were investigated systematically. The photoelectrochemical conversion efficiency recorded for Bi2Te3 is 0.083%.

Simple electrochemical synthesis of black metal oxides for enhanced visible light absorption

Hydrogenation of oxides such as TiO2 is so far considered as a time consuming and complex process which requires high temperature annealing in hydrogen atmosphere. In this work, an electrochemical method for the hydrogenation of metal oxides is introduced. The electrochemical hydrogenation process is a low cost process which requires only a few seconds for synthesizing the black semiconducting oxides. Water with small amount (0.2vol%) of ionic species like fluorine ions is used as electrolyte. The black semiconducting oxides prepared using the electrochemical hydrogenation process exhibit very good absorption of light in visible region.

Electrodeposition of a novel CdTe array on Ni foils and photoelectrochemical performance

A novel perpendicularly aligned CdTe array with cauliflower-like morphology was fabricated on a Ni substrate using a simple electrochemical synthesis method. The samples were characterized by XRD, EDX and FESEM, and the results demonstrate that a high-purity, uniform cauliflower-like CdTe array was obtained. Rod lengths can reach to 3.0 μm, with nanoparticles stacking along the rod growth direction, keeping the diameter at 1.5 μm. A schematic diagram of the possible growth process and evolution from CdTe seed nuclei to the cauliflower-like CdTe array was proposed. The device based on the aligned array-on-Ni configuration demonstrates excellent photoelectrical properties, which is ascribed to the large absorption coefficient of the material and also suggests good electronic structure quality of the cauliflower-like rods. The technique described is applicable to fabricate highly aligned cauliflower-like semiconductor arrays on other conductive substrates.

Synthesis of high-charge capacity triarylamine–thiophene redox electrodes using electrochemical copolymerization

Growing interest in electric transportation and renewable energy generation places a high burden on the development of new materials and devices capable of storing and delivering energy at high rates. We have previously shown that efficient, reversible redox couples can be incorporated in conventional conducting polymers to increase the energy and power density of redox electrodes; and furthermore, that molecular variations can be used to influence the molecular structure thereby enhancing Faradaic charge storage capacity. Here, we show that the energy storage capacity of these conducting polymer electrodes can be increased using electrochemical polymerization of multiple monomers with similar oxidation potentials. Low-cost thiophene monomers are incorporated with triarylamine-derivatives to vary the number of thiophenes and conjugation length between redox-centers. The composition of each monomer is systematically varied to identify the optimal composition that provides the highest charge capacity with reduced cost. Compared to the pure homopolymers, a factor of 2 increase in charge capacity is achieved for copolymers prepared with 10 mol% triarylamine groups using simple electrochemical synthesis. These results indicate that a simple building block approach to conducting polymer electrode design can be achieved when proper consideration is given to the polymer precursors.

Electrochemical synthesis of wheat-like CdSe array and their photoelectrochemical properties

It is reported here that a wheat-like CdSe array on an ITO substrate has been developed by a simple electrochemical synthesis method. These samples were characterized by XRD, EDX and FESEM, whose results demonstrate that a high-purity, uniform hexagonal wheat-like CdSe array was obtained. Photoelectrochemical solar cells are constructed using the wheat-like CdSe array as the photoanode in a polysulphide electrolyte and their power output characteristics are studied. The photoelectric conversion efficiency of the photoelectrochemical solar cells based on the wheat-like CdSe array on an ITO substrate, which are prepared in electrolyte solution containing CdSO4 (0.01 M) + Na2SeO3 (0.01 M) + H2SO4 (0.208 M), can reach a value of 1.15%.

Synthesis and photoelectric characterization of semiconductor CdSe microrod array by a simple electrochemical synthesis method

It is reported here that the microrod array of CdSe on indium doped tin oxide coated conducting glass (ITO) substrate has been developed by a simple electrochemical synthesis method. The electrodeposition of CdSe was also investigated by cyclic voltammetric technique. The sample was characterized by XRD, EDX, FESEM and UV–vis spectroscopic. The X-ray diffraction investigation demonstrates that the CdSe microrod is a uniform hexagonal CdSe crystal. EDX shows that the high purity CdSe is obtained. Field emission scanning electron microscope (FESEM) results show that the microrods’ length, diameter, and direction of growth are nearly uniform and perpendicular to the ITO substrate. UV–vis absorption spectrum study shows the presence of direct transition with the band gap energy 2.13 eV. Photoelectrochemical solar cells are constructed using CdSe microrod array as the photocathode in polysulphide electrolyte and their power output characteristics are studied.

An electrochemical alternative strategy to the synthesis of β-lactams via N [sbnd]C4 bond formation

A simple electrochemical synthesis of β-lactams has been developed using constant current electrolysis in a suitable solvent-supporting electrolyte solutions, with subsequent addition of bromoamides. The regio- and stereo-selectivity of the electrochemically-induced cyclization of bromoamides to β-lactams, via N C4 bond formation, has been evidenced. This synthesis avoids any addition of bases and probases and gives β-lactams in high yields.

Oxidative electropolymerization of pyrrole in the presence of pyridinium chlorochromate

The addition of pyridinium chlorochromate during the electrochemical synthesis of polypyrrole (PPy) significantly accelerates the formation of insoluble polymer. The acceleration of electrochemical polymerization is due to chemical oligomerization of pyrrole by the oxidizing agent as well as the lower oxidation potential of the oligomer compared with the initial pyrrole. Compared with simple electrochemical synthesis the combined method of polypyrrole preparation produces a smaller amount of released gas which results in a doped polymer with a lower conductivity (ca. 10 S cm −1). The conductivity of polypyrrole prepared by chemical oxidation in the presence of pyridinium chlorochromate and tetraethylammonium tetrafluoroborate is about 10 9 times lower than the conductivity of PPy prepared by electrochemical reaction.

Simple electrochemical synthesis of vanadium(II) halides

Vanadium metal dissolves rapidly in a cell Pt/X2 in CH3CN/V (anode) (X = Cl, Br, I) under applied voltages of 5–50 V. The solution phase yields crystalline VCl2. 2CH3CN, VBr2. CH3CN, or VI2; the acetonitrile adducts decompose to VX2 on heating in vacuo. Overall yields of VX2, based on weight of metal dissolved, are 80–90%.