In situ synthesized spherical nickel–silica composite particles for hydrolytic dehydrogenation of ammonia borane

Spherical nickel–silica composite particles were synthesized by sol–gel based method in various solvents followed by in situ activation in aqueous sodium borohydride (NaBH4)/ammonia borane (NH3BH3) solutions. The resulting products prepared in methyl alcohol, ethyl alcohol, and 2-propyl alcohol include spherical particles with the diameters of 600–800, 200–400 nm, and 200–400 nm, respectively. The evolution of 56, 58, and 62 mL hydrogen was finished in about 50, 90, and 65 min in the presence of the spherical nickel–silica composite particles from aqueous NaBH4/NH3BH3, respectively. Introducing additional aqueous ammonia borane solution to the solution including the in situ synthesized particles, the evolution of 58, 50, and 63 mL hydrogen was finished in about 45, 90, and 45 min, respectively, indicating that all the in situ synthesized particles have the recyclability as the catalysts for hydrolysis of NH3BH3. The in situ synthesized particles prepared in methyl alcohol and 2-propyl alcohol show higher rate and amount of hydrogen evolution than in situ synthesized particles prepared in ethyl alcohol.

► In situ activated spherical Ni–SiO2 particles were synthesized in aqueous NaBH4/NH3BH3 solutions. ► The spherical particles show high H2 evolution rate and amount from aqueous NaBH4/NH3BH3 solutions. ► The in situ synthesized spherical particles have the recyclability for hydrolysis of NH3BH3.