Tailoring support surface chemistry to stabilize and modify Ni nanoparticles for accelerated NH3 decomposition reaction kinetics

Supported metal catalysts play a pivotal role in heterogeneous catalysis. However, supported metal species tend to aggregate and grow into large particles during thermal treatment owing to weak metal-support interaction, leading to unsatisfactory catalytic performance for many important catalytic reactions (e.g·NH 3 decomposition). Here we report that tailoring the surface chemistry of SiO 2 by amino-functionalization can effectively enhance the interaction with Ni species, yielding well dispersion of Ni nanoparticles since the strong interfacial bonding restricts the migration and aggregation of metal atoms. Upon support functionalization, the chemical environment of Ni species is also modified, which induces remarkable electronic metal-support interaction. As a result, more Ni 0 sites are exposed, favoring the adsorption of NH 3 and the desorption of N 2 . In addition, the amino ligands can help with the storage and transfer of H atoms from the metallic surface of Ni, resulting in favorable H 2 desorption. All of these effects contribute to superior activity. By contrast, the pristine SiO 2 surface is not suitable for anchoring Ni species due to the weak Ni-SiO 2 interaction. The sintered Ni catalyst after thermal treatment suffers from drastic loss of active surface area and displays poor activity. This work proposes a simple strategy for designing well-dispersed metal catalysts and provides insights into the effects of metal-support interaction on the structure and function of metal catalysts.