Electron-doped perovskite manganite Ca0.9R0.1MnO3 (R=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) polycrystalline samples were prepared and their transport and thermoelectric properties were studied from room temperature to 1000 K. The transport behavior for all the samples is adiabatic small polaron hopping mechanism below 600 K but changes to metallic conductivity at higher temperature. Above 600 K, more 3d electrons of Mn3+ ions will occupy eg orbitals, resulting in the variation in thermoelectric power values. For all the samples, thermoelectric power is only determined by carrier concentration, but resistivity also rests with effective bandwidth. The size matching between Ca2+ and R3+ ions together with heavier R3+ doping can improve thermoelectric performance evidently. Combining these two factors, Ca0.9Dy0.1MnO3 and Ca0.9Yb0.1MnO3 reach ZT=0.2 at 1000 K, suggesting that they can be efficient high temperature n-type thermoelectric oxide materials.

A low-cost impregnation method was developed to prepare PtRu catalysts highly dispersed on carbon support. As clearly revealed by the HRTEM image, even with high metal loadings (up to 40 wt % Pt + 20 wt % Ru) the average particle diameter was 1.5 nm with a narrow distribution ((0.5 nm). Based on EDAX, XRD, XPS, and TGA/DTA analyses, the structure of the PtRu catalyst was deduced to be composed of PtRu alloy and amorphous ruthenium compounds, predominantly hydrous ruthenium oxide, RuO x H y . The PtRu catalyst thusprepared exhibited excellent performance for methanol oxidation.

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