AUTHOR=Zeng Liang , Qing Peilin , Cai Fangfang , Huang Xiantun , Liu Haizhen , Lan Zhiqiang , Guo Jin 

TITLE=Enhanced Hydrogen Storage Properties of MgH2 Using a Ni and TiO2 Co-Doped Reduced Graphene Oxide Nanocomposite as a Catalyst

JOURNAL=Frontiers in Chemistry

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2020.00207

DOI=10.3389/fchem.2020.00207

ISSN=2296-2646

ABSTRACT=<p>To improve the hydrogen storage properties of Mg/MgH<sub>2</sub>, a Ni and TiO<sub>2</sub> co-doped reduced graphene oxide [(Ni-TiO<sub>2</sub>)@rGO] nanocomposite is synthesized by a facile impregnation method and introduced into Mg via ball milling. The results demonstrated that the dispersive distribution of Ni and TiO<sub>2</sub> with a particle size of 20–200 nm in the reduced graphene oxide matrix led to superior catalytic effects on the hydrogen storage properties of Mg-(Ni-TiO<sub>2</sub>)@rGO. The initial hydrogenation/dehydrogenation temperature for Mg-(Ni-TiO<sub>2</sub>)@rGO decreased to 323/479 K, 75/84 K lower than that of the additive-free sample. The hydrogen desorption capacity of the Mg-(Ni-TiO<sub>2</sub>)@rGO composite released 1.47 wt.% within 120 min at 498 K. When the temperature was increased to 523 K, the hydrogen desorption capacity increased to 4.30 wt.% within 30 min. A hydrogenation/dehydrogenation apparent activation energy of 47.0/99.3 kJ·mol<sup>−1</sup> was obtained for the Mg-(Ni-TiO<sub>2</sub>)@rGO composite. The improvement in hydrogenation and dehydrogenation for the Mg-(Ni-TiO<sub>2</sub>)@rGO composite was due to the reduction of the apparent activation energy by the catalytic action of (Ni-TiO<sub>2</sub>)@rGO.</p>