Electrochemical Synthesis Process Research Articles

ADSORPTION OF ACETIC ACID AND THE PROMOTERS OF FORMATION OF PEROXO GROUPS ON PLATINUM AT HIGH ANODIC POTENTIALS

Introduction. Peroxyacetic acid is a strong disinfectant with a wide spectrum of antimicrobial activity. The advantages of peroxyacetic acid are: no stable toxic derivates, the dependence on pH is unsignificant, efficiency and contact time are nondurable. Peroxyacetic acid is produced on an industrial scale by chemical synthesis. The output product requires specific storage conditions. Electrochemical methods of synthesis of peroxyacetic acid are divided into two directions: 1) production of РАА by the cathodic generation of hydrogen peroxide with the presence of acetic acid; 2) production peroxyacetic acid through the anodic oxidation. The advantages of electrochemical synthesis are production of peroxyacetic acid directly “in situ” and synthesis of diluted peroxyacetic acid and acetic acid. The problem of understanding and managing the process of peroxyacetic acid electrochemical synthesis poses the problem of obtaining new data on the component-solution adsorption in the region of high anodic potentials. The aim: to investigate the adsorption of acetic acid and promoters of the formation of peroxo groups on platinum at high anodic potentials. Research methods. The adsorption of acetic acid and peroxo group formation promoters was studied using the charging curves method on the surface of a Pt/PtO electrode. Results. It is shown that the potential shift to the electropositive region leads to a continuous increase in the adsorption of acetic acid along with an increase in the charge of the platinum surface. It is shown that when the electrode potential shifts to the electropositive region, the adsorption of Cl–, Br– and I– ions increases continuously with increasing platinum surface charge. It is shown that the dependence of the adsorption of CNS– ions on the potential has a maximum at ≈ 1.85 V. A further decrease in the adsorption of CNS– ions is associated with a stronger adsorption of their oxidation product – CN–. It has been established that, by the effect on the electrode surface, anions are placed in the CNS– > Cl– > Br– > I– series. Cl–, Br– and I– additives should be used for the electrochemical synthesis of peroxyacetic acid. They contribute to an increase in the current efficiency of the target product in comparison with the initial solution. CNS– additive is not effective. This is explained by the specific adsorption of CNS– ions on the surface of a platinum electrode.

Electrochemical Synthesis of Cu-Cu2o Composite Layers and Its Catalytic Properties Towards Ethylene Generation

Recently a number of articles concerning subjects related to limitation of greenhouse gasses emission or neutralization of greenhouse gasses present in atmosphere significantly increased. Global warming negatively influences on non-failure operation of ecosystem and due to glaciers melting resulting in water volume increase causing raising of water level in seas and oceans. Large number of negative factors resulting from global warming effect creating necessity of performance of intensified investigations going to development of technologies enabling limitation of emission or neutralization of greenhouses gasses through its conversion to chemical compounds which can be applied in synthesis of other useful chemical compounds or functional materials. Other important problem beyond limitation of CO2 amount in atmosphere is related to possibilities of its conversion to chemical compounds which can be used as energy carriers. It creates possibilities for its applications in renewable energy storage oriented systems. The proposed project is focused on photoelectrochemical conversion of one of main greenhouse gas, CO2 to ethylene. The main scientific objective of performed studies was the development of methodology for electrochemical synthesis of binary composite Cu-Cu2O material. Copper is the only metal that exhibits very high selectivity for electrochemical conversion of CO2 to ethylene (1). Ren et al. observed similar effect in case of p-type Cu2O (2). Reported effects allow assumption that combination of both materials can be great solution in the frame of light supported electrochemical conversion of carbon dioxide to ethylene. Authors describe optimization of electrochemical synthesis process towards synthesis of composite coatings of wide composition range. Synthesis conditions were investigated starting from the thermodynamic analysis of the electrolyte. Conditions for synthesis were determined based on the results of voltammetric tests and electrochemical quartz crystal microbalance analyses. Synthesized coatings were characterized towards their composition, structure, morphology and catalytic properties towards electrochemical reduction of CO2 to ethylene. References Y. Kwon, Y. Lum, E. L. Clark, J. W. Ager and A. T. Bell, ChemElectroChem, 3, 1012 (2016).D. Ren, Y. Deng, A. D. Handoko, C. S. Chen, S. Malkhandi and B. S. Yeo, ACS Catalysis, 5, 2814 (2015).P. D. Tran, S. K. Batabyal, S. S. Pramana, J. Barber, L. H. Wong and S. C. J. Loo, Nanoscale, 4, 3875 (2012).

Rapid Synthesis of Yellow Graphite Oxide - One-Step Electrochemical Oxidation of Graphite in Organic Solvents

Graphite oxide is the intermediate in the synthesis of the so-called "miracle material" of the 21st century, graphene. The synthesis of highly oxidized, yellow graphite oxide is hitherto only possible via partially toxic and explosive wet-chemical processes. Therefore, the implementation of the topic graphene in school and university lessons was not possible. Due to the existing risks and the long synthesis time, the currently prevalent synthesis methods of graphite oxide are a major problem not only for teaching but also for scientific research. The authors present a novel electrochemical synthesis process of highly oxidized, yellow graphite oxide, which completely avoids the use of corrosive or toxic substances. The synthesis time is only a few minutes and the preparation of the material can be easily carried out. Therefore, Graphene can now be easily synthesized and taught in school and university.

Silver morphology indicating the evolution of concentration heterogeneity

Heterogeneity is the main problem of scaleups. The common strategy to solve this problem is the enhancement of transport. Here we show an alterative by figuring out the role of heterogeneity and then controlling the heterogeneity for desired products. We employed a gel system to create a diffusion limitation and to discover how the local concentration heterogeneity influences the shape development of silver particles in an electrochemical synthesis process. An interesting phenomenon was observed that the shapes of silver particles were dependent on their location. Silver dendrites were synthesized around the electrode, while polycrystalline spheres were obtained at the forward growth front. The mixture of dendritic and spherical particles was observed between the electrode and the growth front. A temporal evolution of concentration heterogeneity was proposed to interpret the dependence of particle morphology with location. This interpretation was confirmed by regulating the concentration distribution in different gel systems and at different reaction rates. This paper showed that the concentration distribution plays a significant role in the shape development of particles, and controlling the local heterogeneity promises an alternative for the rational synthesis of materials.

Continuous Preparation of Water-Dispersible Magnetite Nanoparticles by Electrochemical Synthesis.

Highly water-dispersible magnetic nanoparticles were synthesized by convenient electrochemical techniques using a continuous flow reactor. The surface properties of the magnetic nanoparticles (MNPs) were modified with hydrophilic organic ligands during the electrochemical synthesis process to control the degree of dispersion in water. The kind of hydrophilic low-molecular weight polymers or surfactants influenced the sizes of the particles ranged between 25-40 nm (in diameter) and their size distribution. Chitosan-modified MNPs exhibited the most uniform particle size distribution among the MNPs synthesized in this study as well as excellent dispersion stability and magnetic properties in water after the crosslinking of the amino groups in chitosan. Especially, the dispersion stability of the MNPs in water was systematically investigated via a light scattering analysis.

Electrochemical Synthesis of Cu-Cu2o-CNT/CNF Composite Coatings

The main scientific objective of performed studies was development of methodology for electrochemical synthesis of ternary composite materials in the Cu-Cu2O-CNT/CNF systems (CNT – carbon nanotubes, CNF – carbon nanofibers). Copper is the only metal that exhibits very high selectivity for electrochemical conversion of CO2 to ethylene (1). Ren et al. observed similar effect in case of p-type Cu2O (2). Reported effects allows on assumption that combination of both materials can be great solution in the frame of light supported electrochemical conversion of carbon dioxide to ethylene. Additionally application of carbon structures: CNT or CNF as charge transfer mediators can limit photodegradation of Cu2O, improving simultaneously its chemical stability (3) and catalytic activity as well as selectivity for electrochemical conversion of CO2 to ethylene (2). Presence of highly hydrophobic CNT/CNF phase in Cu matrix may significantly improve selectivity through limiting adsorption of polar water molecules favoring simultaneously adsorption of nonpolar CO2 molecules. Present studies describing optimization of electrochemical synthesis process towards synthesis of composite coatings of wide composition range. Synthesis conditions were investigated starting from thermodynamic analysis of the electrolyte. In next step, based on zeta potentials values stability of colloidal electrolyte containing carbon nanotubes was analyzed. Current-voltage conditions allowing on deposition of Cu with Cu2O with simultaneous incorporation of CNT/CNF structures were determined based on voltammetric and elctrogravimetric tests. Synthesized coatings were characterized towards their composition, structure and morphology. References Y. Kwon, Y. Lum, E. L. Clark, J. W. Ager and A. T. Bell, ChemElectroChem, 3, 1012 (2016).D. Ren, Y. Deng, A. D. Handoko, C. S. Chen, S. Malkhandi and B. S. Yeo, ACS Catalysis, 5, 2814 (2015).P. D. Tran, S. K. Batabyal, S. S. Pramana, J. Barber, L. H. Wong and S. C. J. Loo, Nanoscale, 4, 3875 (2012).

Conversion of Carbon Dioxide into Ethanol by Electrochemical Synthesis Method Using Cu-Zn Electrode

Research on conversion of carbon dioxide into ethanol has been done. The conversion process is carried out in a sodium bicarbonate electrolyte solution in an electrochemical synthesis reactor. As cathode was used Cu-Zn, while as anode carbon was utilized. Variations of voltage, concentration of sodium bicarbonate electrolyte solution and time of electrolysis were performed to determine the optimum conditions to convert carbon dioxide into ethanol. Sample of the electrochemical synthesis process was analyzed by gas chromatography. From the result, it is found that the optimum conditions of the electrochemical synthesis process of carbon dioxide conversion into ethanol are voltage, concentration of sodium bicarbonate electrolyte solution and time of electrolysis are 3 volts, 0.4 M and 90 minutes with the ethanol concentration of 10.44%.

Ammonia synthesis over yttrium-doped barium zirconate and cerate-based perovskite-type oxide supported ruthenium catalysts

The performance of yttrium-doped barium zirconate and cerate-based perovskite-type oxide supported ruthenium catalysts for the thermal catalytic NH3 synthesis process has been studied; these materials are expected to be applied as electrode catalysts for the electrochemical synthesis process of ammonia (NH3), namely, NH3 electrolysis. The BaZr0.9Y0.1O3-δ (BZY10, with Y substituting for 10 mol% Zr in BaZrO3)-supported Ru catalyst (Ru/BZY10) exhibited a high NH3 synthesis rate (4.00 mmol h−1 g-cat.−1) under the following reaction conditions: S.V. = 36 L h−1 g-cat.−1, T = 400 °C, P = 0.1 MPa. Furthermore, the calcination at 1200 °C of BZY10 enhanced the catalytic performance of Ru/BZY10 (4.63 mmol h−1 g-cat.−1 at 400 °C). Considering the NH3 synthesis rate per Ru amount, the optimal amount of Ru loading was 2.0 wt%. Furthermore, the addition of K and Cs to Ru/BZY10 can further improve the catalyst performance, which is found to be comparable to that of the other reported catalysts and is due to the electron-donating effect to active sites of Ru species. Based on various characterizations, we conclude that the particle size of Ru, the presence of BaCO3 and BaO crystalline phases, and the coverage of Ba species strongly affect the catalyst performance.

The Effects of Voltage and Concentration of Sodium Bicarbonate on Electrochemical Synthesis of Ethanol from Carbon Dioxide Using Brass as Cathode

The effects of voltage and concentration of sodium bicarbonate were investigated to determine the optimum conditions of the electrochemical synthesis process to convert carbon dioxide into ethanol. The conversion process is carried out using a sodium bicarbonate electrolyte solution in an electrochemical synthesis reactor equipped with a cathode and anode. As the cathode was used brass, while as the anode carbon was utilized. Sample of the electrochemical synthesis process was analyzed by gas chromatography to determine the content of the compounds produced. The optimum electrochemical synthesis conditions to convert carbon dioxide into ethanol are voltage and concentration of sodium bicarbonate are 3 volts and 0.4 M with ethanol concentration of 1.33%.

CONVERSION OF CARBON DIOXIDE TO ETHANOL BY ELECTROCHEMICAL SYNTHESIS METHOD USING BRASS AS A CATHODE

The effect of potential and gas flow rate were investigated to determine the optimum conditions of the electrochemical synthesis process to convert carbon dioxide to ethanol. The conversion process is carried out using a NaHCO3 electrolyte solution in an electrochemical reactor equipped with a cathode and anode. As cathode is used brass, while as anode is used carbon. The result of the electrochemical synthesis process was analyzed by gas chromatography to determine the content of the compounds produced qualitatively and quantitatively. The optimum electrochemical synthesis conditions to convert carbon dioxide to ethanol are potential and gas flow rate are 3 volts and 0.5 L/minutes with ethanol concentration yielded 1.32%.

Electrochemical Synthesis of LaSi2 from a NaCl-Naf-LaF3-K2SiF6 Melt at 1023 K

Lanthanum silicides (La5Si4, La5Si3, La4Si, LaSi and LaSi2) are metal-like compounds with semiconductor properties. If this were true, it could become technologically important as an infrared detector material [1]. The possibility of electrochemical synthesis of lanthanum silicides from molten salts were investigated in this work. It can be concluded from thermodynamic calculation that silicon discharge from molten salts more positive than La (~ 0.8 V), in this case electrochemical synthesis possible only in two step, first deposited of Si, next step deposition of La onto Si with formation of lanthanum disilicide: I. 2Si + La(III) +3 e = LaSi2 ΔE0 10233 K = ΔG0 1023 K/ (nF) ≈ 0.500 V,where ΔE0 – is potential (V), ΔG0 - is the Gibbs energy of the reaction I. (J), n – is the number of electrons involved in the reaction (in our case, n = 3), F – is Faraday constant. The electrochemical behaviour of the molten salts system NaCl-NaF-LaF3-K2SiF6 was studied by cyclic voltammetry. A glassy carbon crucible served as a vessel for the melt and as an auxiliary electrode; a W wire was used as the working electrode; the measurements were made with respect to glassy carbon reference electrode 1023 K in argon atmosphere. Typical cyclic voltammogram for molten salts system NaCl-NaF-LaF3-K2SiF6 show two step process of electrochemical synthesis of LaSi2at 1023 K in Ar on W working electrode (Fig. 1 .). On the base of thermodynamic calculation and voltammetric investigation, it has been show that lanthanum disilicide can by electrochemical synthesized from a NaCl-NaF- LaF3-K2SiF6 melt at 1023 K in two step. References R.G. Long, M.C. Bost, J.E. Mahan., Appl. Phys. Lett. 5 3, 1272 (1988). Fig. 1. Voltammogram of a NaCl-NaF-LaF3- K2SiF6 melts on a W working electrode, v= 0.1 V/s. Figure 1

Electrochemical Synthesis of Ammonia Using Proton Conducting Solid Electrolyte and Ru-Doped BaCe0.8Y0.1Ru0.1O3- d Electrode Catalyst

Introduction Recently, the demands for the renewable energy such as water power, wind power, and solar power have increased around the world. These energy production is affected by the climate, and thus, stable power supply is difficult. In addition, the development of technologies of energy storage and transportation is important for effective utilization of the surplus power. Ammonia is a chemical material produced massively and is used in fertilizer and industrial process such as organic synthesis and nitrate acid. In the recent years, ammonia has been paid attention as an energy carrier substance because its hydrogen content and energy density are significantly high. The current process of ammonia production is a Haber-Bosch process. This process, however, requires the high pressure and temperature condition. Thus, a new synthesis process need to be developed. The electrochemical synthesis of ammonia as shown in Fig. 1 is considered to be an effective process of ammonia synthesis from N2 and H2O and/or H2. However, the formation rate of ammonia for the electrochemical synthesis has not been achieved at the demanded level; thus, there are needed to improve ammonia synthesis performance of electrode catalyst and ion conductivity of electrolyte. Therefore, in the present work, to improve the electrochemical synthesis process of ammonia, we have studied the effect of Ru-doping into yttrium-doped barium cerate as an electrode catalyst. Experimental The proton conducting BaCe0.9Y0.1O3- d (BCY) solid electrolyte was synthesized by a co-precipitation method. The BCY powder was mixed with a small amount of NiO as a sintering aid. The resultant powder was uniaxially pressed at 2 MPa into a pellet, followed by cold isostatic pressing at 200 MPa. The pellet was calcined at 1300 ºC for 12 h to obtain BCY pellet. The BaCe0.8Y0.1Ru0.1O3- d (BCYR) was also prepared by the co-precipitation method. The BCY and BCYR powders were mixed with isometric NiO powders by a planetary ball milling, followed by the calcination at 1200 ºC for 5 h. The NiO-BCYR slurry mixed with polyethylene glycol was pasted on one side of the BCY pellet as the cathode, and then, the sample pellet calcined at 1300 ºC for 5 h. After that, The NiO-BCY slurry mixed with polyethylene glycol was pasted on the other side of the pellet as the anode, followed by the calcination at 1300 ºC for 5 h. The powders and pellet were analyzed using X-ray diffraction (XRD), X-ray fluorescence (XRF) and transmission electron microscopy (TEM). Electrochemical synthesis of ammonia was conducted using the single cell fabricated at 500ºC. A gaseous mixture of N2 and Ar was fed into the working and a gaseous mixture of H2 and Ar was fed into the counter. Before the measurement, the Ni-BCY and Ni-BCYR electrodes were well reduced at 600 ºC for 2 h to activate the electrode. Results and discussion According to XRD analysis, both BCY and BCYR samples were assigned to perovskite-type oxides. In addition, Ru component is considered to be doped into BCY, evidenced from XRF and XRD analyses. As a result of electrolysis experiment, ammonia was synthesized electrochemically on the Ni-BCYR electrode. The maximum rate of ammonia formation was ca. 2.0 × 10-10 mol s-1 cm-2 at -600 mV of applied voltage. TEM images indicate that Ru particles existed on the Ni-BCYR surface after the reduction. Therefore, the reason of improvement is probably that the Ru particles on the electrode catalyzes N-N bond breaking. Faradaic efficiency of the ammonia formation was achieved ca. 3.0%, which means that proton on the cathode is mainly converted to hydrogen molecule. Conclusion Electrochemical synthesis of ammonia was carried out using proton conducting solid electrolyte from N2 and H2. Ammonia formation rate was improved by using Ni/BCYR electrode, because doping of Ru component enhances ammonia formation reaction at the cathode. The maximum rate of ammonia formation was ca. 2.0 × 10-10 mol s-1 cm-2 at 500 ºC. Acknowledgments This work was supported by CREST, Japan Science and Technology Agency. Reference [1] S. Giddey, S.P.S Badwal, A Kulkarni, Int. J. Hydrogen Energy 38 (2013) 14576-14594. [2] A. Skodra, M. Stoukides, Solid State Ionics 180 (2009) 1332-1336. [3] H. Iwahara, Solid State Ionics 77 (1995) 289-298. Figure 1

Electrochemical and Thermal Catalytic Syntheses of Ammonia over Yttrium-Doped Barium Zirconate and Cerate Perovskites Supported Ruthenium Catalysts

To resolve a global serious problem on energy consumption by human, the development of various new processes which a renewable energy and a surplus electric power generated from thermal and nuclear power plants are converted to the energy easy to handle is required. As one possible process, a technological process that electrical energy is convert to a chemical substance, so-called energy carrier, is raised. As a candidate of energy carrier, methylcyclohexane (MCH), ammonia (NH3), hydrogen peroxide (H2O2), formic acid (HCOOH) are considered in recent years. In the present work, we have paid attention to NH3. In other words, it is an electrolysis process to produce NH3 from the nitrogen contained in air and the hydrogen supplied by the electrolysis of water. For this electrochemical synthesis process, H2O or H2 is oxidized to proton at the anode, and proton is transported through the proton conducting electrolyte to the cathode. And then, N2 is reacted with proton and reduced to NH3 at the cathode. The lower the operation temperature, the more effective the electrolysis synthesis process of ammonia from N2 and H2O, compared with a conventional Harber-Bosch process. However, the development of solid electrolyte exhibiting high conductivity at lower temperature and the selection of electrode catalyst materials and electrode design to improve the reaction rate of ammonia synthesis for the cathode are required. Therefore, in this study, we have focused on the Ru based catalyst which is well known to be excellent catalysts for thermal catalytic synthesis of ammonia. Furthermore, Ba-Zr-Y and Ba-Ce-Y perovskite-type oxides exhibiting high proton conductivity have been used as a support material to improve the cell performance for electrochemical ammonia synthesis. Firstly, the Ru/Ba-Zr-Y and/or Ba-Ce-Y perovskites solid catalyst was prepared, and its thermal catalytic property for ammonia synthesis was evaluated using a fixed bed flow reactor. As results of comparison tests, Ru/Ba-Zr-Y catalyst showed higher activity than Ru/Ba-Ce-Y catalyst. Furthermore, it was found that an addition of 10wt% of Y component to BaZrO3 perovskite enhances the catalytic performance significantly. And noted that Ru/Ba-Zr-Y catalyst exhibited higher performance than a conventional Ru-Cs+/MgO catalyst. Based on various characterization, we consider that electron transfer from Ba-Zr-Y perovskite to Ru species enhances the dissociation of N-N bond, leading to the high activity for ammonia synthesis. Additionally, in the present work, we have studied the effect of current loading to the catalyst on the catalytic performance for ammonia synthesis to evaluate the applicability of Ru/Ba-Zr-Y catalyst to an electrode catalyst. Acknowledgments This work was supported by CREST, Japan Science and Technology Agency.

Controlled self-assembly of oligomers-grafted fibrous polyaniline/single zirconium phosphate nanosheet hybrids with potential-responsive ion exchange properties

A novel α-zirconium phosphate (α-ZrP) nanosheet-implanted fibrous polyaniline (PANI) hybrid film with potential-responsive ion exchange function is fabricated by a facile pulse electrochemical synthesis technique. The suppression effect of electrical double layer at the conducting substrate/colloidal solution interface for the formation of PANI/α-ZrP hybrid film is effectively improved through a layer of pre-deposited PANI oligomers, whose thickness plays an important role in the self-assembly of the hybrid film. During the pulse electrochemical synthesis process, the oligomers-grafted fibrous PANI is electropolymerized in the period of high potential; and the translucent exfoliated α-ZrP nanosheets are uniformly implanted into the fibrous PANI by electrostatic self-assembly in the following period of low potential. The amount ratio of α-ZrP nanosheet and fibrous PANI can be regulated by adjusting the pulse width based on their growth rate. The results show that the optimized pulse width for the fabrication of PANI/α-ZrP hybrid film with three-dimensional porous structure is 0.8s. Under this condition, the generated PANI/α-ZrP hybrid film shows fast uptake/release ability and high capacity for the separation of Pb2+ ions from aqueous solution based on its unique potential-induced ion exchange process. The adsorption equilibrium time is less than 30s, and the ion exchange capacity of porous PANI/α-ZrP hybrid film reaches 123.5mgg−1, which is almost 9 times higher than that of the compact PANI/α-ZrP hybrid film. Furthermore, the ion exchange capacity retains 85.2% of its initial value after 1000 cycles.

Electrodeposition of cadmium selenide

In the present work the process of electrochemical synthesis of cadmium selenide from sulphate solutions has been examined. Electrode reactions taking place at co-deposition of cadmium and selenium were tested with the use of cyclic voltammetry. Two mechanisms of co-deposition of cadmium and selenium were suggested. Within the range of more positive potentials, the following two reactions take place: reduction of selenious acid to selenium, and then underpotential deposition of cadmium on selenium. The second mechanism proceeds within the potentials range below −0.4V vs. SCE and relies on simultaneous reduction of ions of cadmium and selenious acid in a six-electron process. Next, the influence of selenious acid concentration and potential on the Cd–Se coatings deposition process on copper sheets was examined. The coatings were analysed with X-ray spectrofluorometry, electron scanning microscopy and X-ray diffraction. It was demonstrated that it is possible to obtain coatings stoichiometry corresponding to CdSe compound of hexagonal structure from sulphate electrolyte.

Synthesis of destabilized nanostructured lithium hydride via hydrogenation of lithium electrochemically inserted into graphite

Lithium hydride-graphite composite is synthesized through hydrogenation of lithium intercalated graphite obtained by electrochemical insertion. XRD analysis indicates that the initial graphite is transformed into a mixture of LiC6 and LiC12 by the intercalation of 0.84 lithium for six carbons. After 20 h of hydrogenation under 30 bars at 150 °C, these lithium-inserted compounds are completely transformed into a lithium hydride-graphite composite based on the reaction: Li0.84C6 + 0.42H2 → 0.84LiH + 6C. A weak shift and broadening of the (002) reflex of graphite is observed after the formation of LiH, which is attributed to a small increase of the graphite disorder. Thermal gravimetric analysis coupled with Mass Spectrometry (TG-MS) shows that the desorption of this synthesized nano-LiH starts from around 200 °C, which is much lower than the decomposition temperature (900 °C) of pure LiH. It reveals that this new electrochemical synthesis process of LiH-graphite composites enables an interesting destabilization of the Li–H ionic bond due to a good dispersion of highly divided LiH nanoparticles (below 100 nm) in a carbon matrix. The hydrogen storage capacity of this LiH-graphite composite can be increased by subsequent Li insertion/hydrogenation cycles.

Electrochemical synthesis of nanodimensional powders of neodymium and praseodymium hexaborides and ternary compounds based on neodymium (praseodymium), boron, and metals of the iron triad from chloride-fluoride melts

A process of electrochemical synthesis of nanodimensional powders of neodymium (praseodymium) hexaborides and Pr(Nd)x-Fe(Ni, Co)y-Bz ternary compounds from chloride-fluoride melts is developed. The composition of the fabricated powders is investigated by X-ray phase analysis, and particle sizes are determined using laser diffraction analysis. The dependence of the phase composition of the powders on the temperature, component ratio, current density, and electrolysis potential is established. Optimal conditions of the fabrication process of nanodimensional powders of neodymium and praseodymium borides and Nd11Fe4B4 ternary compound are found.

Nanosized MoO3 as a reusable heterogeneous catalyst for the synthesis of 2,6-bis(benzylidene)cyclohexanones

Abstract Crystalline MoO3 nanoparticles were obtained by electrochemical synthesis process using tetrapropylammonium bromide as a stabilizer and structure-directing agent in ACN:THF(4:1) solvent. Formation of MoO3 nanoparticles took place at a constant supply current of 14 mA/cm2. These synthesized MoO3 nanoparticles were characterized by UV-Vis spectroscopy, FT-IR spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM). So prepared MoO3 nanoparticles were used as a heterogeneous catalyst for the synthesis of 2,6-bis(benzylidene)cyclohexanone derivatives. This protocol offers several advantages, such as simple work-up procedure, recyclability of the catalyst, excellent product yield in a short reaction time and purification of products with a non-chromatographic method.

Electrochemical synthesis of nanosized powders of neodymium and praseodymium hexaborides and ternary compounds based on neodymium (praseodymium), boron and iron group metals from chloride-fluoride melts.

The process of electrochemical synthesis of nanosized neodymium (praseodymium) hexaboride and three-component Pr (Nd) x –Fe (Ni, Co) y –B z com- pound powders from chloride-fluoride melts has been developed. The composition of produced powders is examined by X -ray phase analysis, and particle sizes are measured by laser diffraction analysis. The dependence of powder phase composition on temperature, component relation, current density, and electrolysis potential is established. The optimum conditions of the process of producing nanosized neodymium and praseodymium bo- rides and ternary Nd 1,1 Fe 4 B 4 compound powders are found.

Galvanic deposition of Rh and Ru on randomly structured Ti felts for the electrochemical NH3 synthesis.

Nowadays NH3 is exclusively synthesized by the Haber process. Unfortunately, the energy demand and the CO2 emissions due to H2 production are high. Hydrogen production utilizes precious carbon sources such as coal and natural gas. In the past we proposed an alternative process concept using a membrane electrode assembly in an electrochemical membrane reactor (ecMR). At the anode H2O is oxidized at an IrMMO catalyst to form protons. By applying an external potential to the ecMR N2 is reduced to NH3 at the cathode. Just recently Rh and Ru were identified as possible cathodic electrocatalysts by DFT calculations. We present an easy and highly efficient method for galvanic coatings of Rh and Ru on randomly structured Ti felts to be used in a membrane electrode assembly. Linear sweep voltammetry measurements give a slightly higher activity of Ru for the liquid phase electrochemical NH3 synthesis. The NH4(+) concentration reached is 8 times higher for Ru than for Rh. From an economical point of view, Ru is also more feasible for an electrochemical NH3 synthesis process. Such electrodes can now be evaluated in an ecMR in comparison to recently demonstrated Ti-based electrodes.