2018 Volume 97 Issue 11 Pages 330-335
In this work, we investigated the influence of adding a chelating agent, nitrilotriacetic acid (NTA), on the morphology and activity of spherical silica-nickel composite particles for hydrolytic dehydrogenation of ammonia borane. Their particle sizes prepared with NTA decreased with increasing pH value of the solution used to form the composite particles. The homogeneity of the composite particles prepared with NTA increased with increasing pH value. The hydrogen evolution rate and amount from the aqueous solution containing sodium borohydride (NaBH4) and ammonia borane (NH3BH3) in the presence of the composite particles prepared with NTA did not significantly depend on the pH value. On the other hand, the size and homogeneity of the composite particles depended on the ratio of nickel to NTA. The nickel content of the composite particles increased with increasing the ratio of nickel to NTA, and the composite particles with high ratio of nickel to NTA showed high activity for hydrogen evolution from the aqueous solution containing NaBH4 and NH3BH3. From this and energy-dispersive X-ray spectroscopy (EDX) results, it is suggested that the spherical silica-nickel composite particles prepared with NTA included highly dispersed active nickel species, and showed high activity for hydrogen evolution from aqueous solution containing NH3BH3.