2D NiFe/CeO₂ Basic-Site-Enhanced Catalyst via in-Situ Topotactic Reduction for Selectively Catalyzing the H₂ Generation from N₂H₄·H₂O

An economical catalyst with excellent selectivity and high activity is eagerly desirable for H₂ generation from the decomposition of N₂H₄·H₂O. Here, a bifunctional two-dimensional NiFe/CeO₂ nanocatalyst with NiFe nanoparticles (∼5 nm) uniformly anchored on CeO₂ nanosheets supports has been successfully synthesized through a dynamic controlling coprecipitation process followed by in-situ topotactic reduction. Even without NaOH as catalyst promoter, as-designed Ni_0.6Fe_0.4/CeO₂ nanocatalyst can show high activity for selectively catalyzing H₂ generation (reaction rate (mol_N2H4 mol^–1_NiFe h^–1): 5.73 h^–1). As ceria is easily reducible from CeO₂ to CeO_2–x, the surface of CeO₂ could supply an extremely large amount of Ce³⁺, and the high-density electrons of Ce³⁺ can work as Lewis base to facilitate the absorption of N₂H₄, which can weaken the N–H bond and promote NiFe active centers to break the N–H bond preferentially, resulting in the high catalytic selectivity (over 99%) and activity for the H₂ generation from N₂H₄·H₂O.