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

Abstract

Nickel(0) nanoparticles supported on cobalt ferrite (Ni⁰/CoFe₂O₄), polydopamine coated cobalt ferrite (Ni⁰/PDA-CoFe₂O₄) or silica coated cobalt ferrite (Ni⁰/SiO₂-CoFe₂O₄) are prepared and used as catalysts in hydrogen generation from the hydrolysis of ammonia borane at room temperature. Ni⁰/CoFe₂O₄ (4.0% wt. Ni) shows the highest catalytic activity with a TOF value of 38.3min^-1 in hydrogen generation from the hydrolysis of ammonia borane at 25.0±0.1°C. However, the initial catalytic activity of Ni⁰/CoFe₂O₄ 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 Ni⁰/PDA-CoFe₂O₄ and Ni⁰/SiO₂-CoFe₂O₄ are found to be 7.6 and 5.3min^-1, respectively, at 25.0±0.1°C. Ni⁰/PDA-CoFe₂O₄ catalyst shows high reusability as compared to the Ni⁰/CoFe₂O₄ and Ni⁰/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±0.7nm are well dispersed on the surface of PDA-CoFe₂O₄. .