Supported nickel–iron nanocomposites as a bifunctional catalyst towards hydrogen generation from N2H4·H2O

Abstract

Hydrogen represents an important alternative energy feedstock for both environmental and economic reasons. Development of highly selective, efficient and economical catalysts towards H₂ generation from hydrogen storage materials (e.g., hydrous hydrazine, N₂H₄·H₂O) has been one of the most active research areas. In this work, a bifunctional NiFe-alloy/MgO catalyst containing both an active center and a solid base center was obtained via a calcination–reduction process of NiFeMg-layered double hydroxides (LDHs) precursor, which exhibits 100% conversion of N₂H₄·H₂O and up to 99% selectivity towards H₂ generation at room temperature, comparable to the most reported noble metal catalysts (e.g., Rh, Pt). The XRD, HRTEM and HAADF-STEM results confirm that well-dispersed NiFe alloy nanoparticles (NPs) with diameters of ∼22 nm were embedded in a thermally stable MgO matrix. The EXAFS verifies the electronic interaction between nickel and iron elements in NiFe alloy NPs, accounting for the significantly enhanced low-temperature activity. The CO₂-TPD results indicate that the strong basic sites on the surface of the NiFe-alloy/MgO catalyst contribute to the high H₂ selectivity.