| The high efficient nanoporous Pt-based alloys have been fabricated through mechanical alloying and subsequent dealloying the Al-based precursor alloys. The microstructure and catalytic performance of the nanoporous Pt-based alloys have been characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical measurements.One important strategy is to synthesize Pt-containing nanocatalysts through alloying Pt with other nonprecious metals in order to obtain high efficient catalysts and it is essential to explore their mechanism. The starting Al66Cu30Pt3Ti1, Al66Cu30Pt2Ti2 和 Al66Cu30Pt1Ti3 (nominal composition, at.%) alloys were prepared from pure Al, Cu, Ti and Pt (99.9 wt.%) powders using a planetary ball mill machine and then the precursor alloys were dealloyed in NaOH and HNO3 solutions. Finally, the nanoporous binary PtCu and ternary PtCuTi alloys can be obtained with typical bi-continuous three dimensional structure and high performance for methanol oxidation reaction (MOR) at anode as well as CO tolerance in direct methanol fuel cells (DMFCs).Similarly, nanoporous PtPdAlCu (np-PtPdAlCu) with typical three-dimensional bi-continuous interpenetrating ligament/channel structure alloys have been successfully fabricated from Al80Cu6Ni6Co6Pd1Pt1 precusor alloy. The minor Pt and Pd exist in the Al4CU9 phase in the precursor alloy and the np-PtPdAlCu almost of homogeneous size distribution under 1μm, which was characterized by the X-ray diffraction and electron microscopic characterization analysis. Electrochemical tests indicate that the obtained np-PtPdAlCu alloy exhibits superior electro-catalytic activity towards methanol oxidation reduction (MOR) at anode and oxygen reduction reaction (ORR) activity at cathode.Multi-component nanoporous PtRuCuOsIr (np-PtRuCuOsIr) electrocatalyst has been facilely fabricated by chemical dealloying of mechanically alloyed Al66Cu30(Pt44Ru41Os10Ir5)4 precursor. The np-PtRuCuOsIr catalyst exhibits a typical three-dimensional bi-continuous interpenetrating ligament/channel structure with a length scale of～2.5 nm. Through the XRD analysis we also found the alloying elements (Cu, Os, Ir, Ru) exist in the Pt phase in the form of solid solution. Electrochemical tests indicate that the obtained np-PtRuCuOsIr alloy exhibits superior electro-catalytic activity towards methanol oxidation, enhanced CO tolerance and oxygen reduction reaction activity. Moreover, the np-PtRuCuOsIr alloy shows superior oxygen reduction activities even after 15K cycles, indicating its excellent long-term stability.In multi-component catalyst, Pt accomplishes the dissociative chemisorption of methanol and the alloyed 3d metals form a surface oxyhydroxide which extracts an active oxygen from the water of the acidic electrolyte. On the other hand, the three-dimensional bi-continuous nanoporosity with interconnected channels and nano-sized ligaments provides excellent transport paths for all involved ions, molecules and electrons. |
