抄録
Hollow nickel-silica spheres were synthesized by sol-gel method followed by in-situ activation in aqueous sodium borohydride (NaBH4) /ammonia borane (NH3BH3) solutions. The evolution of 38, 58, and 41 mL hydrogen was finished in about 125, 90, and 30 min from aqueous NaBH4/NH3BH3 solution in the presence of nickel-silica spheres precursor activated with the amount of NaBH4 = 5, 10, and 20 mg, respectively. Morphology of in-situ synthesized samples depends on the amount of NaBH4, and the hollow spheres were obtained with the medium amount of NaBH4. Particle size and wall thickness of the hollow spheres were controlled by adjusting ratio of ethyl alcohol to water, and the particle size and wall thickness decrease with increase of the ratio. The evolution of 44, 49, and 58 mL hydrogen from aqueous NaBH4/NH3BH3 solution was finished in about 45, 35, and 90 min in the presence of the in-situ synthesized hollow spheres obtained from the precursors prepared with ratio of ethyl alcohol to water = 3.3, 10, and 20, respectively. The results indicate that the amount of hydrogen evolution increases with increase of ratio of ethyl alcohol to water. Otherwise, the amount of hydrogen evolution was related with reducibility of the precursors.
