Graphene oxide supported oxygen vacancy-rich Co3O4 and Ni nanoparticle for boosting the hydrogen storage properties of MgH2

Abstract

Developing efficient catalysts is pivotal for advancing MgH₂-based hydrogen storage systems. In this study, a novel catalyst, graphene oxide-supported oxygen vacancy-rich Co₃O₄ and Ni nanoparticles (Ni-O_V-C@GO), was synthesized to enhance the hydrogen storage performance of MgH₂. The catalyst dramatically improved the kinetics of MgH₂, lowering the initial hydrogen desorption temperature of Ni-O_V-C@GO-MgH₂–7 to 438 K, which is 386 K lower than that of as-milled MgH₂. The composite achieved 5.0 wt% hydrogen absorption at 423 K within 600 s and retained 97.3 % capacity after 30 cycles. Notably, the activation energy for H₂ desorption was reduced to 40.78 kJ/mol, an 80 % decrease compared to pristine MgH₂. The in-situ formation of CoMg₂/CoMg₂H₅ and Mg₂Ni/Mg₂NiH₄ acted as “hydrogen pumps”, facilitating multiple hydrogen transfer pathways. Additionally, oxygen vacancies elongated Mg-H bonds, enhancing dehydrogenation kinetics through catalytic effects. These findings provide valuable insights into improving hydrogen adsorption and desorption kinetics in MgH₂-based systems.