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Magneli phase titanium sub-oxide conductive ceramic TiO was used as the support for Pt due to its excellent resistance to electrochemical oxidation, and Pt/TiO composites were prepared by the impregnation-reduction method. The electrochemical stability of TiO was investigated and the results show almost no change in the redox region after oxidation for 20 h at 1.2 V (vs NHE) in 0.5 mol/L HSO aqueous solution. The catalytic activity and stability of the Pt/TiO toward the oxygen reduction reaction (ORR) in 0.5 mol/L HSO solution were investigated through the accelerated aging tests (AAT), and the morphology of the catalysts before and after the AAT was observed by transmission electron microscopy. At the potential of 0.55 V (vs SCE), the specific kinetic current density of the ORR on the Pt/TiO is about 1.5 times that of the Pt/C. The LSV curves for the Pt/C shift negatively obviously with the half-wave potential shifting about 0.02 V after 8000 cycles AAT, while no obvious change takes place for the LSV curves for the Pt/TiO. The Pt particles supported on the carbon aggregate obviously, while the morphology of the Pt supported on TiO remains almost unchanged, which contributes to the electrochemical surface area loss of Pt/C being about 2 times that of the Pt/TiO. The superior catalytic stability of Pt/TiO toward the ORR could be attributed to the excellent stability of the TiO and the electronic interaction between the metals and the support. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the osseointegration of domestic porous tantalum-niobium(PTa-Nb) alloy., Methods: A total of 36 adult New Zealand rabbits were selected and divided into 3 groups. Pta-Nb rods(3.5 mm×10 mm) were implanted into the femoral condyle of each rabbit.The rabbits were sacrificed successively at 4,8,12 weeks after operation. X-ray, hard tissue slices stained with toluidine blue, scanning electron microscope(SEM), X-ray energy disperse spectroscopy(XEDS) and push-out test were used to test the osseointegration of PTa-Nb. SPSS19.0 software package was used for statistical analysis., Results: X-ray films showed no obvious inflammation,as well as implants loosing and bone resorption. Density of the bone around implants increased. Hard tissue slices displayed chimeric shape in the implant-bone interface. New bone contacted directly to the surface of PTa-Nb and got more and more closer with the increase of healing time. Osteoid formed in the inner pores at 4 weeks after operation,and more mature bone tissue grew into inner part of PTa-Nb at 12 weeks. SEM showed bone tissue was more denser and closer to the Pta-Nb,which was similar to the results of hard tissue slices. XEDS analysis showed the percent content of the calcium and phosphate of the tissue within PTa-Nb increased gradually in the three groups.The ratio of Ca/P at 8 and 12 weeks was significantly higher than at 4 weeks (P<0.05); Push-out test showed the shear-strength of PTa-Nb implants increased from (8.26±0.75) MPa at 4 weeks to (21.04±1.46) MPa at 12 weeks (P<0.05)., Conclusions: The domestic PTa-Nb alloy has good osseointegration with both bone tissue ongrowth and ingrowth,which may be a high potential biomimetic bone material.