Synthesis of nanocomposite Pd balls and wires by chemical vapor infiltration

Our study presents the preparation of well-defined Pd nanoballs and nanowir es using the different pore size of cubic and hexagonal shaped MCM type mes oporous silicate materials as matrix templates. The synthesis involves load ing the organometallic precursor into template matrix via chemical vapor in filtration (CVI), followed by mild thermal decomposition to generate Pd met als self-organized inside the template. For Pd@MCM-48, the Pd metal forms s pherical domains (similar to 38 nm) consisting of three dimensionally inter connected into Pd arrays; for Pd@SBA-15 and Pd@MCM-41, the Pd metal forms o f one-dimensional wires. Etching out the matrix produces porous Pd nanoball s (pore sizes of similar to1.5 - 2.0 nm) with retaining original domain siz es of similar to 38 mn; similarly Pd@SBA-15 and Pd@MCM-41 afford freestandi ng Pd nanowires. In addition, phase transition behavior and melting point d epression of the Pd nanowires is studied.