Calcium-Decorated Graphene-Based Nanostructures for Hydrogen Storage

TL;DR

This study uses first-principles calculations to explore calcium-decorated graphene nanostructures as potential high-capacity hydrogen storage materials, highlighting stable Ca adsorption and multiple H2 binding.

Contribution

It demonstrates that calcium atoms can be stably adsorbed on graphene edges and bind multiple hydrogen molecules, offering a promising approach for hydrogen storage.

Findings

Ca atoms prefer zigzag edges of graphene with no clustering

Up to six H2 molecules can bind per Ca atom with ~0.2 eV/H2

Ca-decorated ZGNR can reach ~5 wt % hydrogen capacity

Abstract

We report a first-principles study of hydrogen storage media consisting of calcium atoms and graphene-based nanostructures. We find that Ca atoms prefer to be individually adsorbed on the zigzag edge of graphene with a Ca-Ca distance of 10 A without clustering of the Ca atoms, and up to six H2 molecules can bind to a Ca atom with a binding energy of ~0.2 eV/H2. A Ca-decorated zigzag graphene nanoribbon (ZGNR) can reach the gravimetric capacity of ~5 wt % hydrogen. We also consider various edge geometries of the graphene for Ca dispersion.