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.