Nickel(0) nanoparticles supported on bare or coated cobalt ferrite as highly active, magnetically isolable and reusable catalyst for hydrolytic dehydrogenation of ammonia borane

Nickel(0) nanoparticles supported on cobalt ferrite (Ni-0/CoFe2O4), polydopamine coated cobalt ferrite (NP0/PDA-CoFe2O4) or silica coated cobalt ferrite (NP0/SiO2-CoFe2O4) are prepared and used as catalysts in hydrogen generation from the hydrolysis of ammonia borane at room temperature. Ni-0/CoFe2O4 (4.0% wt. Ni) shows the highest catalytic activity with a TOF value of 38.3 min(-1) in hydrogen generation from the hydrolysis of ammonia borane at 25.0 +/- 0.1 degrees C. However, the initial catalytic activity of Ni-0/NCoFe204 catalyst is not preserved in subsequent runs of hydrolysis. Coating the surface of cobalt ferrite support with polydopamine or silica leads to a significant improvement in the stability of catalysts. The TOF values of Ni-0/PDA-CoFe2O4 and Ni-0/(2)-CoFe2O4 are found to be 7.6 and 5.3 min(-1), respectively, at 25.0 +/- 0.1 degrees C. Ni-0/PDA-CoFe2O4 catalyst shows high reusability as compared to the Ni-0/CoFe2O4 and NP0/SiO2-CoFe2O4 catalysts in hydrolytic dehydrogenation of ammonia borane at room temperature. All the catalysts are characterized by using a combination of various advanced analytical techniques. The results reveal that nickel nanoparticles with an average size of 12.3 +/- 0.7 nm are well dispersed on the surface of PDA-CoFe2O4. (C) 2017 Elsevier Inc. All rights reserved.