Electrochemical hydrogen storage behavior of Ni-Ceria impregnated carbon micro-nanofibers

A hierarchical porous structured carbon micro-nanofiber containing the bimetallic configuration of the nickel (Ni) and ceria (CeO₂) nanoparticles (NPs) was synthesized and tested for the electrochemical hydrogen (H₂) storage capacity. The electrode exhibited a high H₂ storage capacity of 498 mA h/g or 1.858% (w/w) at the charge-discharge current density of 500 mA/g. A mechanistic insight showcased the combined contributions of the high surface area containing activated carbon microfiber (ACF) substrate, the graphitic carbon nanofibers (CNFs), and the Ni and CeO₂ NPs, towards the augmented electrochemical H₂ storage capacity and cyclic stability of the fabricated Ni–CeO₂–CNF/ACF electrode. Ni served as the catalyst for growing the CNFs via chemical vapor deposition as well as for storing H₂ via spillover mechanism, while CeO₂ created the charge carrier vacancies in the material. The measured cycle retention capacity of 99% and charge-discharge efficiency of 97.6% confirm the electrochemically stable characteristics of Ni–CeO₂–CNF/ACF, and clearly indicate it to be an economically viable and efficient H₂-storage material.