Nanoceria supported cobalt(0) nanoparticles: a magnetically separable and reusable catalyst in hydrogen generation from the hydrolysis of ammonia borane

Abstract

Cobalt(0) nanoparticles supported on nanoceria (Co⁰/CeO₂) were prepared from the reduction of cobalt(II) ions impregnated on the surface of ceria nanopowders. The magnetic Co⁰/CeO₂ catalyst could be isolated from the reaction solution by using a magnet and characterized by using ICP-OES, XRD, TEM, EDX, BET and XPS techniques. The results reveal that cobalt nanoparticles with particle sizes in the range between 3.5 and 6.0 nm were successfully anchored on the surface of nanoceria. Co⁰/CeO₂ is a magnetically separable and reusable catalyst in hydrogen generation from the hydrolysis of ammonia borane retaining its initial catalytic activity (TOF = 7.0 min⁻¹) even after the fifth use. For comparison, other non-noble metal nanoparticles were also supported on nanoceria. Ni⁰/CeO₂ and Cu⁰/CeO₂ provide TOF values of 1.7 min⁻¹ and 1.5 min⁻¹, respectively, while Fe⁰/CeO₂ is catalytically silent in the hydrolysis of ammonia borane at room temperature. The work reported here also includes the results of a kinetic study of the catalytic hydrolysis of ammonia borane depending on the temperature and catalyst concentration.