(73g) Dissociation of Water on Defective Carbon Substrates

Carbon nanostructures can be synthesized in a wide variety of sizes and shapes, which makes them attractive to carry out chemical reactions taking advantage of shape-catalytic effects. The graphene surfaces that make up these structures are, however, chemically inert toward most substances. If these materials are to be used as catalytic supports, they would have to be made chemically active by either functionalization, doping, or inducing structural defects.

In a recent paper [1], we have shown using ab initio calculations how a vacancy site on a carbon surface can induce the thermal splitting of water at relatively low temperatures. The interaction between water and the vacancy gives rise to a complex reaction network where 7 different intermediates can be formed. In this work we present a complete study of the full reaction network, including the kinetics for all the reaction steps and the equilibrium distributions of reactants and products for the reaction happening on a graphene surface. We also examine the dissociation on a vacancy site on a nanotube surface, which shows the shape-catalytic effect of the surface curvature. These results illustrate how the shape of the reacting material can be used to improve reaction yields.

[1] M.K. Kostov, E.E. Santiso, A.M. George, K.E. Gubbins, M.B. Nardelli, Phys. Rev. Lett. 95, 136105 (2005)