Graphene oxide supported oxygen vacancy-rich Co3O4 and Ni nanoparticle for boosting the hydrogen storage properties of MgH2
Yazhou Wang, Yongpeng Xia, Enyong Xu, Cuili Xiang, Qing Xue, Zexuan Yang, Fen Xu, Lixian Sun, Yong Shen Chua, Yongjin Zou
Abstract
• We synthesized a novel catalyst composed of Co 3 O 4 with oxygen vacancies and Ni nanoparticles supported on graphene oxide. • Initial dehydrogenation temperature of MgH 2 is significantly reduced to 165 °C. • Incorporating Ni-O V -C@GO into MgH 2 greatly accelerate its hydrogen storage kinetics. • Catalytic activities arises from the formation of active species and the presence of oxygen vacancies. Developing efficient catalysts is pivotal for advancing MgH 2 -based hydrogen storage systems. In this study, a novel catalyst, graphene oxide-supported oxygen vacancy-rich Co 3 O 4 and Ni nanoparticles (Ni-O V -C@GO), was synthesized to enhance the hydrogen storage performance of MgH 2 . The catalyst dramatically improved the kinetics of MgH 2 , lowering the initial hydrogen desorption temperature of Ni-O V -C@GO-MgH 2 –7 to 438 K, which is 386 K lower than that of as-milled MgH 2 . 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 H 2 desorption was reduced to 40.78 kJ/mol, an 80 % decrease compared to pristine MgH 2 . The in-situ formation of CoMg 2 /CoMg 2 H 5 and Mg 2 Ni/Mg 2 NiH 4 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 MgH 2 -based systems.