Size evolution of palladium nanoparticles from low-temperature solvated atoms

Abstract

Palladium nanoparticles were synthesized by the chemical liquid deposition method. In this method Pd atoms, produced by resistive heating, were co-deposited at 77 K with 2-propanol vapors to obtain a frozen metal-organic matrix, which is then melted to obtain a colloidal dispersion. In this work, we study the effect of the melting or warm-up rate of the frozen matrix on the characteristics of nanoparticles. The colloidal dispersions were characterized by FTIR, TEM and HRTEM techniques. The FTIR spectra reveal that the carbonaceous fragments are anchored on Pd particles. Studies in TEM and HRTEM micrographs reveal higher mean particle size (∼5 nm), broader size distributions and irregular shapes when the melting process is faster, whereas for a slower warm-up process, it was found smaller particle sizes (∼2 nm), narrower size distributions and regular particle shapes like cuboctahedron, tetrakaidecahedron and icosahedron.