Ultrafine Ru nanoparticles embedded in SiO2 nanospheres: Highly efficient catalysts for hydrolytic dehydrogenation of ammonia borane

Ru@SiO2 core-shell structured nanospheres have been prepared via a one-pot synthetic route in a NP-5/cyclohexane reverse micelle system and characterized by XRD, SEM, TEM, N2 adsorption-desorption, and H2 temperature programmed desorption. The characterized results show that ultrafine Ru nanoparticles (NPs) of around 2 nm are effectively embedded in the center of well-proportioned spherical and porous silica nanospheres (∼25 nm in diameter). Interestingly, the number of Ru NPs increases inside the spherical particles of SiO2 as the increase of Ru loading. The as-synthesized Ru@SiO2 exhibits high catalytic activity and good durability for hydrogen generation from the aqueous of ammonia borane (AB) complex under ambient atmosphere at room temperature. The hydrolysis activation energy of Ru@SiO2 was estimated to be about 38.2 kJ mol−1, which is lower than most of the reported activation energy values for the same reaction using many different Ru-based and other noble metal containing catalysts, indicating the superior catalytic performance of these core-shell structured nanospheres.