Synergetic Catalysis of Non-noble Bimetallic Cu-Co Nanoparticles Embedded in SiO2 Nanospheres in Hydrolytic Dehydrogenation of Ammonia Borane

摘要

Ultrafine non-noble bimetallic Cu-Co nanoparticles (similar to 2 nm) encapsulated within SiO2 nanospheres (Cu-Co@SiO2) have been successfully synthesized via a one-pot synthetic route in a reverse micelle system and characterized by SEM, TEM, EDS, XPS, PXRD, ICP, and N-2 adsorption desorption methods. In each core shell Cu-Co@SiO2 nanosphere, several Cu-Co NPs are separately embedded in SiO2. Compared with their monometallic counterparts, the bimetallic core shell nanospheres CuxCo1-x@SiO2 with different metal compositions show a higher catalytic performance for hydrogen generation from the hydrolysis of ammonia borane (NH3BH3, AB) at room temperature, due to the strain and ligand effects on the modification of the surface electronic structure and chemical properties of Cu-Co NPs in the SiO2 nanospheres. Especially, the Cu0.5Co0.5@SiO2 nanospheres show the best catalytic performance among all the synthesized CuxCo1-x@SiO2 catalysts in the hydrolytic dehydrogenation of AB. In addition, the activation energy (E-a) of Cu0.5Co0.5@SiO2 core shell structured nanospheres for the hydrolysis of AB is estimated to be 24 +/- 2 kJ mol(-1), relatively low values among the bimetallic catalysts reported for the same reaction. Furthermore, the multi-recycle test shows that the bimetallic Cu0.5Co0.5@SiO2 core shell nanospheres are still highly active for hydrolytic dehydrogenation of AB even after 10 runs, implying a good recycling stability in the catalytic reaction.