Ammonia-Induced Exsoluted-Co Nanoparticles Derived from Defected SrCoO_2.5 for Ammonia Decomposition

Ammonia serves as a promising energy carrier for hydrogen storage and transport, with zero carbon emissions during hydrogen release. Co-based catalysts are considered promising candidates for ammonia decomposition, but their low activity and poor stability remain key challenges. Herein, oxygen-deficient SrCoO_2.5 (SCO) was synthesized, and the effects of different atmospheres (NH₃, H₂, and N₂) on the in situ exsolution of Co nanoparticles (NPs) were investigated. The structure evolution under different atmospheres was characterized by ex situ XRD. The SCO-NH₃ catalyst (prepared by in situ exsolution under NH₃) demonstrates superior performance with 57.6% NH₃ conversion at 550 °C under a WHSV of 30,000 mL g_cat^-1 h^-1. This represents 1.5- and 1.8-fold enhancements compared with the SCO-H₂ and SCO-N₂ catalysts, respectively. In addition, the structure-performance relationship and potential reaction mechanisms were investigated through comprehensive characterizations.