Magnesium Supported on Nickel Nanobelts for Hydrogen Storage: Coupling Nanosizing and Catalysis

Abstract

Magnesium nanoparticles with the mean particle size of ∼18 nm were synthesized through the thermal decomposition of di-n-butylmagnesium using Ni nanobelts as a catalyst and support with the aim of improving the hydrogen storage properties of magnesium by coupling nanosizing and catalysis. Full hydrogenation of the magnesium nanoparticles was achieved at a low temperature of 100 °C, and hydrogen release occurred at ∼230 °C. The material showed fast hydrogen absorption with good structural stability during cycling. Hydrogen desorption occurred in 200 min at 250 °C. These enhanced hydrogen storage properties were assigned to a lower activation energy (69.2 ± 2.5 kJ mol–1 H2), and the remarkably low enthalpy of hydrogenation (34.4 ± 5.4 kJ mol–1 H2) although partially compensated by a reduced entropy of 76.9 ±5.4 J K–1 mol–1 H2. The improvement of both kinetics and thermodynamics is believed to result from the coupling effects of nanosizing and catalysis.