A DFT study of hydrogen peroxide reduction reaction on a carboxyl functionalized graphene sheet

G. L. LUQUE, M. I. ROJAS, E. P. M. LEIVA

Cancún

Congreso; International Materials Research Congress IMRC XIX; 2010

Graphene, a single layer of  bonded carbon atoms closely packed in a honeycomb two-dimensional lattice, has attracted considerable attention from both the experimental and theoretical scientific communities since it was discovered and successfully isolated from bulk graphite just a few years ago [1]. It has striking physical and chemical properties, such as high surface area, fast electron transfer rate, high thermal conductivity, excellent mechanical strength, good biocompatiblility [2] and low cost fabrication. These properties make it a promising material for the applications in nanocomposites, in particular in electrochemical sensors being a perfect alternative electrode material to carbon nanotubos.
In the present work, the adsorption of hydrogen peroxide on pristine and modified graphene sheets is studied by means of Density Functional Theory (DFT) calculations. The system involves perfect and defective layers which can be pristine or functionalized with carboxyl groups. We consider Stone-Wales (SW) defects which are common types of stable sidewall defects on carbon nanotubes and graphene. The chemical functionalization of these surfaces with carboxyl groups modifies their physical and chemical properties [3], so it is of technological importance to understand where this functionalization takes place and how the properties change. We find that functionalization increases (in absolute value) the adsorption energy of hydrogen peroxide and improves its reduction reaction. The electric properties and the mechanism of the reduction reaction of hydrogen peroxide on these surfaces are studied. The local minima where found through the conjugate gradient (CG) technique, employing DFT calculations with spin polarization (sp) as implemented in SIESTA [4]. In order to study the minimum energy path for the present reaction and determine the energy barriers we performed state-of-the-art calculation methods using the nudged elastic band method (NEB) [5].

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