Room temperature chemical deposition of palladium nanoparticles in anodic aluminium oxide templates

Palladium nanoparticles are deposited in the pores of freestanding, mesoporous anodic aluminium oxide (AAO) templates via a chemical route at room temperature. In the precursor, Pd2+ ions are complexed with ammonia and reduced to Pd0 by adding an excess amount of formaldehyde. To enhance the infiltration of pores with the precursor, 2-propanol is added to the solution. After a few hours of plating at room temperature, crystalline Pd0 nanoparticles with an average size of ~4 nm form on the pore walls of the AAO templates. The effect of heat treatment on the structure of the AAO/Pd system is also studied. The specimens are investigated using FESEM, EFTEM/EDX, and electron and x-ray diffraction techniques. Preliminary catalyst activity analyses reveal good selectivity of ~90%, but low conversion of ~1.2% of carbon monoxide to methane in hydrogen flow at 330 °C on AAO/Pd. The oxidized form of the catalyst shows instantaneous oxidation with ~100% selectivity and conversion of carbon monoxide to carbon dioxide in oxygen flow at 140 °C.