Search results for "cathode"

Electronic effects in the production of smali dianionic gold clusters by electron attachment on to stored Au-n, n = 12-28

1999

Abstract Single charged gold clusters Au n -, 12  n  28, are stored in a Penning trap, size selected and transformed into dianions, Au2- n by the application of an electron beam. At the onset of dianion production, that is that range of cluster sizes n where the smallest doubly charged clusters are observed, the measured intensity ratio of the dianions to their precursors is not a continuous function of cluster size. Instead, there is a strong odd-even effect and a comparatively intense signal of Au2-18 The observed structures are very reminiscent of similar phenomena in the abundance spectra of metal clusters as observed by Knight et al. (1984, Phys. Rev. Lett., 52, 2141), which gave ris…

Transient color centers in complex oxide crystals

2005

The present work is devoted to investigation of induced by a pulsed electron beam (E = 0.25 MeV, τ = 10 ns) transient color centers in pure Gd3Ga5O12, YAlO3 and LiNbO3 single crystals. The relaxation of induced absorption of the crystals was studied within 0-5000 ns range. The origin and nature of transient color centers responsible for induced absorption was discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

First Observation of Doubly Charged Negative Gold Cluster Ions

1999

Singly charged gold cluster anions in the size range n = 16–30 have been captured, stored and size selected in a Penning trap. After application of an electron beam doubly charged gold cluster anions have been observed for 20 ≤ n ≤ 30. To our knowledge this is the first observation of metal cluster dianions. The threshold appearance size is in good agreement with a simple charged sphere model. The application of argon gas pulses simultaneously with the electron beam is found to increase the production rate by an order of magnitude.

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…

Nuovi materiali per celle a combustibile ad ossidi solidi a temperatura intermedia (IT-SOFC): sintesi, caratterizzazione e correlazione struttura-pro…

2014

Photocatalytic and photoelectrocatalytic H2 evolution combined with valuable furfural production

2023

In this work the photocatalytic (PC) and photoelectrocatalytic (PEC) reforming of furfuryl alcohol (FA) under environmental friendly conditions was investigated. Both H2 evolution and partial oxidation to furfuraldehyde were followed. For the first time TiO2 based photocatalysts were studied and the photocatalytic activity of home prepared photocatalysts was compared with that of commercial ones under both UVA and simulated solar irradiation. PEC tests were performed by using home prepared TiO2 nanotubes (TiO2 NTs) as photoanode and Pt free Ni foam as cathode to improve the Hydrogen Evolution Reaction (HER). Both the partial FA oxidation reaction rate and H2 evolution rate were normalized f…

The influence of sludge retention time on mixed culture microbial fuel cell start-ups

2017

Abstract In this work, the start-ups of air-cathode microbial fuel cells (MFCs) seeds with conventional activated sludge cultivated at different solid retention times (SRTs) are compared. A clear influence of the SRT of the inoculum was observed, corresponding to an SRT of 10 days to the higher current density exerted, about 0.2 A m −2 . This observation points out that, in this type of electrochemical device, it is recommended to use high SRT seeds. The work also points out that in order to promote an efficient start-up, it is not only necessary to use high SRT seeds, but also to feed a high COD concentration. When feeding 10,000 ppm COD and keeping SRT of 10 d differences of current densi…

Optimization of the performance of an air–cathode MFC by changing solid retention time

2017

BACKGROUND This work is focused on the optimization of the performances of air-cathode microbial fuel cells (MFC) by changing the solid retention time (SRT) of the suspended biomass culture. RESULTS Five MFCs inoculated with activated sludge obtained from a municipal wastewater treatment plant were fed with a highly-concentrated acetate solution (10 000 ppm COD) and operated over two-month tests in order to determine how SRT may influence the performances of the bio-electrogenic cells. The MFC operated at SRTs of 2.5 days was found to outperform the other cells, operated at SRT of 1.4, 5.0, 7.4 and 10.0 days. In order to evaluate the possibility of using SRT as a manipulated parameter for t…

Electrochemical Conversion of Dichloroacetic Acid to Chloroacetic Acid in Conventional Cell and in Two Microfluidic Reactors

2013

The electrochemical conversion of dichloroacetic acid to chloracetic acid is investigated in conventional cells and in microreactors. Two different microreactors are used: the first is a filter press cell equipped with PTFE micrometric spacers, easy to assemble and disassemble and available for a large variety of electrodes and solvents; the second is made using an adhesive spacer, micromilling and press and could easily be developed on an industrial scale. The electrochemical synthesis is performed successfully in the microreactors equipped with a graphite cathode under proper operative conditions. The performance of the process strongly depends on the nature of the cathode and, for micror…

Electrochemical reduction of carbon dioxide to formic acid at a tin cathode in divided and undivided cells: effect of carbon dioxide pressure and oth…

2016

Abstract The reduction of carbon dioxide to formic acid at a tin cathode was studied in both divided and undivided cells. In the first stage of the study, the effect of some operating parameters, including the working potential and the nature of the supporting electrolyte and of the cathode, on both the cathodic reduction of CO2 and the anodic oxidation of formic acid was investigated in a divided cell. In a second stage, the reduction of carbon dioxide was performed in an undivided cell with the aim of studying the effect on the generation of formic acid of various operating parameters such as current density, cathode to anode area ratio, mixing rate and nature of the anode and of the supp…