Silica aerogel-supported cobalt nanocomposites as efficient catalysts toward hydrogen generation from aqueous ammonia borane

Abstract

In this study, a mesoporous silica aerogel-supported cobalt (Co/SAG) nanocomposite synthesized by a facile chemical reduction was used as an alternative catalyst for hydrogen generation from aqueous NH₃BH₃. The result showed that Co/SAG exhibited 41% higher hydrogen generation rate for the NH₃BH₃ hydrolysis than the ordered mesoporous silica (MCM-41)-supported Co catalysts (Co/MCM-41) prepared by the same reduction method. This is attributed to the fact that the Co nanoparticles were smaller (less than 5 nm in diameter) and better-deposited in SAG than MCM-41 as observed in the TEM micrographs. It is also found that the Co/SAG catalyst delivered superior turnover frequency (3013 ml H₂ min⁻¹ g_metal⁻¹) and activation energy (46.4 kJ mol⁻¹) than most of the Co-based catalysts reported. This study showed that the Co/SAG prepared is a potential non-precious catalyst for hydrogen generation from aqueous NH₃BH₃.