Biomedical Engineering Reference
In-Depth Information
attention given to graphene for novel carbon-based nanoscaled
devices has revived interest in the chemical modification of this
carbon material. Furthermore, from a more academic perspective,
hydrogenation of graphene is a direct bridge that links concepts
in organic chemistry to the possible applications in solid state
engineering.
Our primary motivation for investigating hydrogen in graphene
is to be able to realize high hydrogen uptakes on carbon materials.
In order to achieve this, it is always beneficial to know how the road
to adsorption saturation on the surface looks in terms of the physical
mechanisms involved, and how one can control the required reactions.
This chapter discusses systems involving hydrogen in chemisorbed
states on graphene, which have been studied through theoretical
modeling of the electronic structure. We outline our recent findings
that are crucial to understand graphene defects brought about by
hydrogen, which serves as a benchmark for covalently adsorbed
molecules on carbon surface. Significant discussion is also focused
on the extension to bilayer graphene systems, which approximate
the graphite bulk and basal surface.
In this chapter we first review the established facts regarding
the adsorption of hydrogen atoms on graphene, followed by a
discussion of hydrogen molecule dissociative adsorption on the
surface and graphene edge defects. Section 5.4 details the stability
of the smallest hydrogen clusters on the graphene surface, followed
by a discussion on the effects of adsorbed hydrogen on the electronic
states of graphene and applications using tunneling microscopy.
Section 5.6 focuses on maximizing graphene's adsorption properties,
allowing hydrogen access to both faces. We finally give a summary
and present concluding remarks on open areas for research we are
interested in.
5.2
The H Atom and Graphene
Studies on the chemical modification of graphene by adding the
adsorbed species on one or both faces of graphene have been carried
out for a wide range of purposes. Reactions with NO and NH
, for
example, have been studied for sensing applications, while studies
involving the adsorbed metals have been carried out in addressing
the post-silicon electronics demands. On the latter, recent studies
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