Lead ruthenium oxide pyrochlore

J.-M. Zen, A. S. Kumar and J.-C. Chen, Electrochemical Behavior of Lead-Ruthenium Oxide Pyrochlore Catalyst Redox Characteristics in Comparison with that of Ruthenium Dioxide, J. Mol. Catal. A Chem. 165 (2001) 177-188. 

Zen, J.M., Kumar, A.S., and Chen, J.C., Electrochemical behavior of lead-ruthenium oxide pyrochlore catalyst Redox characteristics in comparison with that of ruthenium dioxide, J. Mol. Catal. A, 165, 177, 2001. 

It should be noted that the exact cation stoichiometry of the product is highly sensitive to the exact metal concentration of the ruthenium source solution and temperature and pH of the reaction medium (inadvertent increases in both of these parameters lead to increased solubility of lead in the alkaline reaction medium and consequently yield solid products of lower lead ruthenium ratios). While synthesis of a pure lead ruthenium oxide pyrochlore is relatively easy, the precise cation stoichiometry of the product is a property that is not always easy to control. A relatively quick check on the cation stoichiometry of the lead ruthenium oxide product can be obtained, however, by using the correlation between lattice parameter and composition that is displayed in Fig. 1. When lattice parameter and cation stoichiometry are independently determined, the relationship shown in Fig. 1 also provides an assessment of product purity since data points that show significant departures from the displayed linear correlation indicate the presence of impurity phases. The thermal stability of the lead ruthenium oxides decreases with increasing occupancy of tetravalent lead on the octahedrally coordinated site, but all of the ruthenium oxide pyro-chlores described are stable to at least 350° in oxygen. 

Enzyme-like behavior was observed for electrocatalyt-ic oxidation on Nafion/lead-ruthenium oxide pyrochlore chemically modified electrodes.Nafion is loaded with lead(II) and ruthenium(III) cations by ion exchange, and then their oxides are prepared by in situ precipitation in such a way that the catalytically active sites remain... 

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Ruthenium pyrochlore oxides, mixed oxides of ruthenium and bismuth or lead with the general formula A2+xRu2.x07.y (A = Pb or Bi 0 < x < 1 0 < y < 0.5) catalyze the oxidative cleavage of vic-diols to the corresponding... 

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