Enhanced reversible hydrogen storage in palladium hollow spheres

Abstract

Palladium has long been used as a hydrogen sponge because of its ability to store hydrogen under ambient conditions (room temperature and 1 bar pressure). However, Pd suffers from a low storage capacity. The current investigation pertains to the enhancement in the reversible hydrogen storage capacity of Pd, by using hollow sphere geometry. Additional storage is achieved in molecular form; thus utilizing a recently developed multi-mode storage strategy. Hollow spheres, which can be viewed as nanocontainers, have been synthesized using a chemical reduction method (outer diameter of ∼300 nm and shell thickness ∼20 nm). Pressure-composition-isotherms have been used to characterize the hydrogen storage capacity and to establish the reversibility of the process. A 54% enhancement in the reversible storage capacity (25 °C and 140 bar) is observed in the case of Pd hollow spheres as compared to that of bulk Pd and 70% with respect to that of nanoporous Pd. The outer and inner surfaces of the hollow sphere play contrasting catalytic roles in the absorption and desorption process.

Keywords:

• Hydrogen storage
• nano hollow structure
• pressure composition isotherms

Acknowledgments

We thank Jai Singh, Advanced Imaging Center, I.I.T Kanpur for facilitating TEM.

Additional information

Funding

The authors would like to acknowledge financial assistance from Science and Engineering Research Board, Department of Science and Technology (SERB-DST), India under Grant No. EMR/2016/004987.