Ce-enhanced nano-Ni exsolution from Ni-Al-O spinel oxide enables facile fabrication of CeO2-Ni interaction for efficient ammonia decomposition

Ammonia decomposition is an appealing method for on-site hydrogen production, enabling ease of transportation and storage of H 2 . However, the high-temperature and hydrogen-rich environment present a challenge in developing highly efficient and stable catalysts. Hence, this study outlines an exsolution strategy for synthesizing a Ni-based catalyst in intimate contact with CeO 2 . The Ce 10 /NiAl 2 O 4 catalyst exhibits competitive catalytic performance for ammonia decomposition reaction, and achieves a hydrogen production rate of 78.3 mmol g cat −1  min −1 at 550 °C. Importantly, the robust structure of the Ce 10 /NiAl 2 O 4 catalyst ensures that no significant deactivation is observed during the 200-h stability test. HRTEM, XRD, TPD and kinetic studies reveals that the presence of CeO 2 enhances the dispersion of exsolved Ni nanoparticles, modulates the surface basicity of catalyst, reduce the reaction activation energy, promote the desorption of nitrogen/hydrogen species, and subsequently promotes NH 3 adsorption/activation capacity·NH 3 -TPD-MS in combination with in-situ DRIFTS demonstrate that CeO 2 could accelerate the recombination and desorption of N* adatoms, which is the rate limiting step, thereby significantly boosting catalytic performance. Furthermore, the DFT calculations reveal that the interaction between CeO 2 and Ni species facilitates electron transfer toward Ni, lowering the barrier for both N–H dissociation and N* recombination and desorption. This work not only presents an efficient and stable noble-metal-free catalyst for ammonia decomposition to generate hydrogen, but also provide a general strategy to engineer high-performance catalysts applicable to harsh catalytic environments.