Nonthermal Plasma Synthesis of Ammonia over Ni-MOF-74

Herein, we demonstrate a synergistic approach with radiofrequency plasma to synthesize ammonia in the presence of Ni-MOF-74 as catalyst. The Ni-MOF displayed higher ammonia yields as compared to the pure Ni metal. Specifically, ammonia yields as high as 0.23 g-NH3 (g-catalyst·kWh)−1 and energy cost of 265 MJ mol–1 over Ni-MOF were observed. The enhanced catalytic activity of the Ni-MOF in the presence of plasma was attributed to the presence of pores, which improved mass transfer of guest and product molecules during reaction, the presence of open Ni metal sites, and lower surface hydrogen recombination. Furthermore, the ammonia energy yield of our plasma-Ni MOF catalyst is superior to those of the state-of-the-art RF plasma catalytic systems.