CeO2/Ni Inverse Catalyst as a Highly Active and Stable Ru-free Catalyst for Ammonia Decomposition

Catalytic ammonia decomposition is an efficient way to produce clean hydrogen, but the design of ammonia decomposition catalysts is limited by the high cost of noble metals and the low activity. Herein, we report a CeO2/Ni inverse catalyst prepared by the coprecipitation method, exhibiting a high hydrogen production rate of 79.6 mmol gcat–1 min–1 at 500 °C, which is better than traditional supported Ni-based catalysts and even many of the Ru-based catalysts reported in the literature. In addition, this inverse catalyst showed catalytic stability for 100 h continuous reaction at 600 °C. Systematic catalyst characterizations revealed that the inverse CeO2/Ni catalyst exhibits small cerium oxide nanoparticle islands supported on the Ni nanoparticles. The inverse structure confers enhanced metal–support interaction and abundant Ni-CeO2 interface sites, which facilitate the generation of highly concentrated oxygen vacancies and abundant electron-rich Ni atoms at the interface under reduction conditions. These features endow the CeO2/Ni inverse configuration possessing increased number of adsorption sites for NH3 molecules, enhancing N–H bond breaking, and facilitating the recombination desorption of N and H adatoms, thereby accelerating the reaction rate. This work highlights the significance of constructing a rational configuration between the active metal nanoparticles and oxides to enhance the catalytic efficiency for NH3 decomposition.