Core–shell Co@SiO2 nanosphere immobilized Ag nanoparticles for hydrogen evolution from ammonia borane†
Abstract
Silver nanoparticles (NPs) immobilized by core–shell Co@SiO2 nanospheres (Co@SiO2/Ag) have been in situ generated during the hydrolysis of ammonia borane (AB). The as-synthesized Co@SiO2/Ag nanocomposites (NCs) were characterized by XRD, SEM, TEM, EDX, SAED, ICP, XPS and the N2 adsorption–desorption techniques. It is found that well dispersed silver NPs (∼2 nm) were successfully immobilized on core–shell Co@SiO2 nanospheres. The resulting Co@SiO2/Ag NCs exhibited a superior catalytic activity for hydrogen generation from hydrolysis of AB, as compared to that of Co@SiO2, free Ag, and the physical mixture of Co@SiO2 and Ag NPs. The hydrolysis activation energy for Co@SiO2/Ag NCs was measured to be approximately 25.6 kJ mol−1, which is lower than most of the reported values for the same reaction by other catalysts, indicating the superior catalytic performance of the Co@SiO2/Ag NCs.