Ammonia Cracking Catalyzed by Ni Nanoparticles Confined in the Framework of CeO₂ Support

For the extraction of hydrogen from ammonia at low temperatures, we investigated Ni-based catalysts fabricated by the thermal decomposition of RNi₅ intermetallics (R = Ce or Y). The interconnected microstructure formed via phase separation between the Ni catalyst and the resulting oxide support was observed to evolve via low-temperature thermal decomposition of RNi₅. The resulting Ni/CeO₂ nanocomposite exhibited superior catalytic activity of ∼25% at 400 °C for NH₃ cracking. The high catalytic activity was attributed to the interlocking of Ni nanoparticles with the CeO₂ framework. The growth of Ni nanoparticles was prevented by this interconnected microstructure, in which the Ni nanoparticles incorporated nitrogen owing to the size effect, whereas Ni does not commonly form nitrides. To the best of our knowledge, this is a unique example of a microstructure that enhances catalytic NH₃ cracking.