Nickel-induced structure transformation in hydrocalumite for enhanced ammonia decomposition

Modifying the material structure of catalysts and determining how the structure controls their catalytic activities are critical topics in heterogeneous catalysis research. Herein we report that the structure of hydrocalumite-layered double hydroxides (CaAl-LDHs) can be tuned by gradually introducting Ni2+. It was revealed that the gradual introduction of Ni2+ in hydrocalumite led to a structure-transformation process, which introduced hydrombobomkulite and eventually evolved into takovite. Compared with the case without structure-transformation process, the structure-transformation catalysts showed excellent NH3 decomposition activity after high-temperature reduction. Moreover, the obtained catalysts showed a relatively high conversion per Ni weight compared with other reported oxide-supported Ni catalysts. This study demonstrates the feasibility of preparing LDHs-based heterogeneous catalysts by modulating the material structure through induced structure-transformation process.