Self-protective cobalt nanocatalyst for long-time recycle application on hydrogen generation by its free metal-ion conversion

Cobalt nanoparticles have attracted much attention in nanocatalysis due to their low cost and high activities. However, the easy-oxidative deactivation of cobalt nanocatalysts in air seriously limits their practical applications, especially in a long-time recycle application. Herein, by intentionally taking advantage of the readily oxidizable character of metallic cobalt, we describe a simple but efficient method to overcome the above obstacle through a free and reverse metal-ion conversion of cobalt in air at room temperature. With this novel method, the cobalt nanocatalyst demonstrates the superior activity even after the long-time (73 days) recycle application for hydrogen generation from ammonia borane.