Enhancing hydrogen storage properties of MgH2 by core-shell CoNi@C

Abstract

Introducing multicomponent nanoparticles can improve remarkably de/hydrogenation kinetic properties of MgH2. In this work, the original core-shell CoNi@C bimetallic nanoparticles were obtained via hydrothermal and calcination reduction technology. MgH2-8 wt% CoNi@C starts to dehydrogenate at 173 °C with the dehydrogenation capacity of 5.83 wt% within 1800 s at 275 °C. Moreover, the composite absorbs 4.83 wt% H2 within 1800 s at 100 °C with prominent advantage at low temperature. The notable improvement of hydrogen storage properties of MgH2 is attributed to the reversible phase transitions of Mg2Co/Mg2CoH5 and Mg2Ni/Mg2NiH4, and the excellent thermal conductivity and confinement effect of the carbon shell. As a result, the apparent activation energy of dehydrogenation reaction reduces to 78.5 kJ/mol. This work extends the horizon of bimetallic nanoparticles with especial microstructure for enhancing the hydrogen storage properties of metal hydrides.