Catalytic NH3 decomposition has drawn growing interest in constructing the NH3-based hydrogen economy. Ni catalysts show great potential in this reaction but suffer from low atom utilization efficiency and unclear structure–activity relationship. Here, atomic layer deposition was used to grow Ni clusters on CeO2 nanorods to create a highly active catalyst for NH3 decomposition, which outperforms the conventional Ni nanoparticle catalysts and the synthesized Ni single-atom catalyst. The distinct catalytic behaviors of Ni clusters and Ni single atoms were systematically investigated. It is revealed that the interfacial confinement effect induces a strong electronic interaction between Ni clusters and CeO2, wherein abundant Ov-Ce3+ sites are formed in the vicinity of Ni clusters, resulting in interfacial electron-enriched Niδ− sites. These Niδ− sites bind to N adatoms moderately, favoring N–H bond cleavage and nitrogen desorption (the rate-determining step), which is the origin of the high activity. In contrast, ionic Ni single atoms diffusing into the CeO2 lattice display a much lower activity since strongly bound N adatoms block the active sites and retard the overall rate. This work provides a deep understanding of Ni-catalyzed NH3 decomposition and paves the way for designing high-performance metal catalysts for other structure-sensitive reactions.
NH 3 decomposition is receiving increased attention for on-site CO x -free H 2 generation. Unfortunately, the harsh reaction conditions often cause sintering of active metals. Here we report a simple method to achieve well Ni dispersion by nano-structuring the BN support with La species. The surface reaction-induced LaBO 3 nano-islands on BN support have a strong affinity for Ni atoms, which can capture and confine Ni species to yield a large population of well dispersed Ni clusters and nanoparticles. The Ni species selectively anchored on LaBO 3 islands expose more active sites and boost desorption of N 2 and H 2 , exhibiting superior activity and stability for NH 3 decomposition. In addition, it is revealed that the Ni dispersion is sensitive to the change of the support surface structure. These findings highlight the important role of support structure in determining the nature of the metal phase and provide guidance for designing catalysts with controlled catalytic structure and reactivity.
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