Influence of hydrogen spillover effect on the properties of Ni particles prepared by ultrasonic spray pyrolysis

Ideally spherical non-agglomerated Ni particles (mean diameter 1.10μm) were prepared by ultrasonic spray pyrolysis of NiCl 2 aqueous solution in the presence of 0.1 mass percent of Pd in an H 2 -N 2 atmosphere at 900°C., Incomlete reduction of the NiCl 2 aqueous solution in the absence of additives was observed under the same experimental conditions. Promotional influence of Pd was explained in terms of hydrogen spillover effect. Morphology of Ni particles was analyzed by using scanning tunneling microscopy. Decrease of mean surface roughness was found upon addition of Pd. Differential scanning calorimetry revealed significant increase of hydrogen absorption by Ni particles prepared in the presence of Pd(−ΔH=8390Jg −1 ) compared with the results for Ni particles prepared without additives (−ΔH=108Jg −1 ).