Anode Modification Research Articles

Surface modification of a MCFC anode by electrodeposition of yttrium

Porous nickel has been used as the anode for MCFCs; its performance is relatively satisfactory, but still not perfect. For example its electrocatalytic activity, sintering resistance, creep resistance etc., must be increased. To date, Ni-Cr, Ni-Co or Ni-Cu alloys have been considered as possible anode materials. On the other hand, the effective catalytic characteristics of rare earth metals have made them recognized as potent alloying elements; for example, the possibility of lanthanide-nickel alloy as a hydrogen occlusion material. In this study, an attempt has been made to modify nickel anode surfaces by electrodepositing yttrium, to improve the anodic polarization behaviour of the nickel electrode. The result shows that the anodic polarization performance of the electrodes can be improved significantly by electrodeposition of yttrium. The improvement of anodic polarization behaviour of the modified nickel electrode appears to derive from improvement of the wetting properties of the electrode.

Anodic Modification of Lignins during Electrolysis in the Organocell Process

Pulping liquor from the 5 t/day demonstration plant of Organocell GmbH, Munich, was electrolyzed. The analysis of the isolated lignins revealed considerable changes of lignin structure during electrolysis. These changes included polymerization reactions involving the formation of C- and O-condensed interunit linkages and reactions of the side-chain such as decomposition of enol ethers and increase of COOH, CO and OH ali. groups. The extent of the observed reactions was fond to be highly dependent on the current density

Two-color x-ray generator for detection of aluminum by differential absorption

Development and calibration of a high-intensity, ‘‘two-color’’ x-ray source for application to differential absorption measurements of aluminum is described. The output intensity from this source is predominantly in two atomic emission lines: the aluminum and silicon Kα lines at 1.49 and 1.74 keV, respectively. Anode fabrication techniques and modifications to a commercial rotating anode x-ray generator necessary to achieve this unique source are detailed. Measurements made with an ionization chamber suggest that the output intensity of the aluminum Kα line is 1.1×109 photons/s mm2 at a distance of 60 mm from anode center when operated at 20 kV and 10 mA. The aluminum line intensity was about 50% of the silicon line. These same techniques can be readily adapted to produce a variety of selected atomic line spectra for differential absorption diagnostics of other species of interest.

Time dependence of the asymmetric resistance of polycrystalline β″-alumina

The time dependence of the asymmetric dc resistance for certain polycrystalline β″-alumina tubes was investigated by cyclic voltammetry and current pulse techniques. Various compositions were studied as representative of the different types of behavior; asymmetric resistance with time dependence (9.6% Na 2O, 0.75% Li 2O), asymmetric resistance without time dependence (8.6% Na 2O, 1% MgO, 0.5% Li 2O), and symmetric resistance (8.85% Na 2O, 0.75% Li 2O). Asymmetry appears to be caused by the anodic modification of an initially present film to a thin passivating film of Na 2O. Film conversion occurs more slowly for the first material.

The electrochemical formation and electron spectroscopic characterization of the platinum sulfide electrode

The anodic voltammetry of acetonitrile solutions containing hydrogen sulfide shows that modification of the platinum electrode surface occurs at potentials sufficiently anodic to oxidize hydrogen sulfide (≥1.25 V vs. SCE). The cathodic voltammetry of these electrodes which have been subjected to anodic polarization shows the reductive discharge of the modified surface at −0.70 V vs. SCE. Comparison of the electron energy (e.s.c.a.) spectra of the modified surface with those of various authentic samples indicates that the anodic modification of the surface is the oxidative formation of PtS.

The electrochemical formation and electron spectroscopic characterization of the platinum sulfide electrode

Summary The anodic voltammetry of acetonitrile solutions containing hydrogen sulfide shows that modification of the platinum electrode surface occurs at potentials sufficiently anodic to oxidize hydrogen sulfide (≥1.25 V vs . SCE). The cathodic voltammetry of these electrodes which have been subjected to anodic polarization shows the reductive discharge of the modified surface at −0.70 V vs . SCE. Comparison of the electron energy (e.s.c.a.) spectra of the modified surface with those of various authentic samples indicates that the anodic modification of the surface is the oxidative formation of PtS.