First-principles insight into hydrogen adsorption over Co4 anchored on defective graphene

The interaction of hydrogen with graphene-supported Co-4 was studied by first-principles calculation, with a particular focus on the role of support defects in modulating the adsorption properties of hydrogen. It is shown that point defects in graphene can effectively improve the capacity of Co-4 for hydrogen storage by modifying the interactions between metal cluster and supports, but exert different effects. By virtue of excellent structural stability and favorable hydrogen uptake, Co-4 decorated on defective graphene with dopant N accompanying with C-vacancy stand out as promising hydrogen storage media, and such a better performance is more likely relating to a lower d-band center of supported-Co-4. This work explores the possibility of Co-4-decorated defective graphene sheets as hydrogen storage materials through introducing the appropriate defects in support.