Efficient low-temperature ammonia cracking enabled by strained heterostructure interfaces on Ru-free catalyst

Abstract

Ammonia (NH3) has emerged as a promising liquid carrier for hydrogen (H2) storage. However, its widespread adoption in H2 technology is impeded by the reliance on costly Ru catalysts for low-temperature NH3 cracking reaction. Here, a strained heterostructure Co@BaAl2O4−x core@shell catalyst is reported that demonstrates catalytic performance at low reaction temperatures comparable to most Ru-based catalysts. This catalyst exhibits exceptional activity across a range of space velocity conditions, maintaining high conversion rates at 475 to 575 °C and achieving an impressive H2 production rate of 64.6 mmol H2 gcat−1 min−1. Synchrotron X-ray absorption spectroscopy, synchrotron X-ray diffraction, and kinetic studies are carried out to elucidate the dynamic changes of the strained heterostructure interface of Co-core and BaAl2O4−x-overlayer under catalytic working conditions. The performance enhancement mechanisms are attributed to the tensile strained Co surface encapsulated in the defective BaAl2O4−x, which enhances NH3 adsorption and facilitates the rate-determining N─H dissociation. Furthermore, the strain release and restoration during NH3 dehydrogenation enable efficient nitrogen desorption, preventing active site poisoning. This work highlights the effectiveness of lattice strain engineering and the development of synergistic strong metal-support interfaces between active metal nanoparticles and oxide support to boost low-temperature NH3 cracking. Graphical abstract: [Figure not available: see fulltext.]