Search results for "Electrochemical"
showing 10 items of 574 documents
Electrocatalytic carboxylation of chloroacetonitrile at a silver cathode for the synthesis of cyanoacetic acid
2008
Abstract The electrocatalytic carboxylation of chloroacetonitrile to cyanoacetic acid performed at silver cathodes was investigated both theoretically and experimentally. Silver exhibits powerful electrocatalytic activities towards the reduction of chloroacetonitrile. In CO 2 -saturated CH 3 CN, reduction of NCCH 2 Cl occurs at potentials that are about 0.7 V more positive than those observed at glassy carbon and gives cyanoacetic acid in good yields. Theoretical considerations on the effect of operative parameters on the performances of the process were confirmed by electrocarboxylation experiments performed in undivided cells equipped with sacrificial anodes both in a bench-scale electroc…
Direct electrochemical detosylation of tetratosylcyclen to cyclen with carbon cathodes
2005
The electrochemical detosylation of tetratosylcyclen to cyclen (1,4,7,10-tetraazacyclododecane) in aprotic solvents at a carbon cathode was investigated both in a bench-scale batch electrochemical reactor and in a continuous batch recirculation reaction system equipped with a parallel-plate electrochemical cell. Yields and faradaic efficiency in cyclen, respectively, of 80 and 55% were obtained in the bench-scale reactor working in acetonitrile. It was found that the faradaic efficiency in cyclen depends on the competition between the reduction of the tetratosylcyclen and parasitic processes as the reduction of the tetraalkylammonium cations present in the supporting electrolyte. We have ob…
Electroreduction of aliphatic chlorides at silver cathodes in water
2010
The effect of water on the reduction of aliphatic chlorides at silver cathodes was investigated by cyclovoltammetric experiments in acetonitrile, water and their mixture and focused electrolyses in water solutions. The addition of water to acetonitrile gives rise to the formation of new peaks and/or the displacement of pre-existent peaks at dramatically less negative potentials. In a water medium, silver shows a very large electrocatalytic effect towards the reduction of chlorinated aliphatic compounds belonging to the classes of chloromethanes, chloroethanes and chloroethenes, dramatically higher than that observed in aprotic solvents such as dimethylformamide (DMF) or acetonitrile (ACN). …
Coadsorption of NRR and HER Intermediates Determines the Performance of Ru-N4 toward Electrocatalytic N2 Reduction
2021
Efficiency of the electrochemical N2 reduction reaction (NRR) to ammonia is seriously limited by the competing hydrogen evolution reaction (HER) but our current atomic-scale insight on the factors controlling HER/NRR competition are unknown. Herein we unveil the elementary mechanism, thermodynamics, and kinetics determining the HER/NRR selectivity on the state-of-the-art NRR electrocatalyst, Ru-N4 using constant potential density functional theory calculations (DFT). The calculations show that NRR and HER intermediates coadsorb on the catalyst where HER is greatly suppressed by the NRR intermediates. The first reaction step leading to either *NNH or *H determines the selectivity towards NRR…
Electrochemical characterization of mangrove sediments: A proposal of new proxies for organic matter oxidation
2019
Abstract The voltammetric response of microparticulate deposits resulting from solvent evaporation of ethanolic extracts of mangrove sediments in contact with aqueous acetate buffer is hereby described. Dated sediment cores sampled from the Peruvian mangrove system (“Manglares de Tumbes” National Sanctuary) presented voltammetric responses dominated by oxidative signals of organic components that exhibit significant variations depending on the depth. Voltammetric data allowed for the definition of electrochemical indexes representative of the electrochemically oxidable organic matter fraction. These electrochemical indexes were fEAOM (for the total amount of organic matter being electrochem…
Renewable energies driven electrochemical wastewater/soil decontamination technologies: A critical review of fundamental concepts and applications
2020
Abstract Electrochemical wastewater and soil treatments are exciting set of technologies that has been well-studied over the recent years as one of the most-effective remediation techniques for the removal of hazardous pollutants from liquids effluents and soil. The main requirement of these technologies is electricity and their sustainability can be largely improved if they are powered by renewable energy sources. Likewise, this green energy powering can help to apply these technologies in remote areas, such as rural communities in developing countries, where no electricity grid is available. This review presents a comprehensive discussion on fundamental concepts and applications of renewa…
Simple, Fast, Bright, and Stable Light Sources
2012
In this work we show that solution-processed light-emitting electrochemical cells (LECs) based on only an ionic iridium complex and a small amount of ionic liquid exhibit exceptionally good performances when applying a pulsed current: sub-second turn-on times and almost constant high luminances (>600 cd m(-2) ) and power efficiencies over the first 600 h. This demonstrates the potential of LECs for applications in solid-state signage and lighting.
A simple low-cost highly reproducible method of fabricating optical fiber tips for a photon scanning tunneling microscope
1996
Influence of mobile ions on the electroluminescence characteristics of methylammonium lead iodide perovskite diodes
2016
In this work, we study the effect of voltage bias on the optoelectronic behavior of methylammonium lead iodide planar diodes. Upon biasing the diodes with a positive voltage, the turn-on voltage of the electroluminescence diminishes and its intensity substantially increases. This behavior is reminiscent of that observed in light-emitting electrochemical cells (LECs), single-layer electroluminescent devices in which the charge injection is assisted by the accumulation of ions at the electrode interface. Because of this mechanism, performances are largely independent from the work function of the electrodes. The similarities observed between planar perovskite diodes and LECs suggest that mobi…