Acceptor‐Doped Cerium Oxides Enabling Metallic Nanocatalyst Exsolution for Hydrogen Production From Ammonia

The development of advanced catalysts with enhanced activity and durability is essential for driving sustainable hydrogen production through ammonia cracking. In this sense, exsolution has gained prominence for generating stable and active nanoparticles socketed into the oxide support with high resistance to sintering. However, challenges remain in expanding these methods to CeO 2 ‐based systems due to the limited solubility of transition metals in fluorite oxides. Here, it is demonstrated that incorporating Gd into the CeO 2 lattice enhances the successful dissolution of Ru and Rh, promoting the exsolution of highly dispersed metallic nanoparticles (∼3 nm), including RuRh alloys. The resulting Ru‐exsolved@Ce 0.8 Gd 0.2 O 2‐δ catalyst exhibits remarkable catalytic activity and long‐term stability in ammonia decomposition for 260 h, outperforming Ru‐impregnated catalysts. In addition, benchmarking against literature values demonstrates that the Ru‐exsolved@Ce 0.8 Gd 0.2 O 2‐δ are among the most active catalysts at 400 °C. This work highlights the potential of lattice modification of CeO 2 ‐based catalytic supports via acceptor doping, resulting in significant metal‐exsolution dispersion and remarkably active catalysts for hydrogen generation via ammonia decomposition, with potential applications that can be expanded to other (electro)catalytic systems.