The Role of BaCO3 on Ni-BaZrO3 Catalysts for Efficient NH3 Decomposition

Abstract Barium zirconate (BaZrO3) is a versatile material that has recently gained attention as a catalyst support for ammonia decomposition. In this study, an innovative synthesis strategy for BaZrO3 is combined with a solvent-free dry-milling method to deposit nickel onto its surface. The resulting Ni-BaZrO3 catalyst exhibited superior performance in ammonia decomposition for COx-free hydrogen production, outperforming both traditionally synthesized BaZrO3-based systems and more conventional Ni-supported catalysts. Comprehensive material characterization─using XRD, N2 adsorption–desorption, ATR, and Raman spectroscopy─confirmed that the new synthesis route improves the structural and chemical properties of the perovskite compared to conventional methods. H2-TPR and CO2-TPD analyses revealed that exploiting superficial BaCO3 reduction to BaO enhanced surface defectivity, and a high density of basic sites interacting with Ni nanoparticles can be obtained, facilitating electron exchange between the support and the metal. The mechanism of BaO formation and interaction with CO2 in TPD was deeply analyzed using in situ characterization techniques. Further mechanistic insights into product formation and release were obtained via TPSR and DRIFTS, emphasizing the critical role of metal-support interaction through the formation of Ni-BaO entities on the catalyst surface. Overall, this work demonstrates a sustainable and scalable route for producing high-performance Ni-BaZrO3 catalysts and advances the understanding of their reactivity, focusing on the importance of the metal-support interplay and reinforcing their potential in green hydrogen production through ammonia decomposition.