Deposition of Ru-Ni-S nanoparticles on carbon by spray-pyrolysis: Effects of solvent and other processing parameters

Nanoparticles of Ru-Ni-S were synthesized in a single-step spray-pyrolysis process as potential catalysts for fuel cells and other applications. The liquid precursors containing ruthenium, nickel, and sulfur were nebulized by an ultra-sonic atomizer to generate aerosol droplets, which were subsequently decomposed to form uniformly distributed nanoparticles for deposition on a carbon thin film. It was observed that the application of methanol as solvent has a strong effect on the particle morphology, size, and composition. The morphology of the Ru-Ni-S nanoparticles changed from spherical with water as solvent, to dendrites upon increase in the methanol concentration in the precursor solution. It was also found that the pyrolysis temperature strongly affected the particle morphology when methanol was used as solvent. High temperatures promote dendrite formation. When a water/methanol mixture was used as solvent, crystalline ternary nanoparticles of Ru-Ni-S on a carbon layer were formed at lower temperatures. A very interesting and unique structure of spherical clusters of crystalline particles attached by a chain of crystalline nanoparticles was synthesized. Elemental analysis obtained with EDS attached to the SEM used for particle characterization has confirmed the existence of all elements of interest, and X-ray mapping showed all elements were distributed uniformly in the nanoparticles.