Sujata Paul

First-principles analysis of electron-phonon interactions in graphene

The electron-phonon interaction in monolayer graphene is investigated using density-functional perturbation theory. The results indicate that the electron-phonon interaction strength is of comparable magnitude for all four in-plane phonon branches and must be considered simultaneously. Moreover, the calculated scattering rates suggest an acoustic-phonon contribution that is much weaker than previously thought, revealing an important role of optical phonons even at low energies. Accordingly it is predicted, in good agreement with a recent measurement, that the intrinsic mobility of graphene may be more than an order of magnitude larger than the already high values reported in suspended samples.

Sequestration and selective oxidation of carbon monoxide on graphene edges

The versatility of carbon nanostructures makes them attractive as possible catalytic materials, as they can be synthesized in various shapes and chemically modified by doping, functionalization, and the creation of defects in the nanostructure. Recent research has shown how the properties of carbon nanostructures can be exploited to enhance the yield of chemical reactions such as the thermal decomposition of water (Kostov et al 2005 Phys. Rev. Lett. 95) and the dissociation of methane into carbon and hydrogen (Huang et al 2008 J. Chem. Phys. at press). In this work, we consider the carbon-mediated partial sequestration and selective oxidation of carbon monoxide (CO), both in the presence and absence of hydrogen. Using first-principles calculations we study several reactions of CO with carbon nanostructures, where the active sites can be regenerated by the deposition of carbon decomposed from the reactant (CO) to make the reactions self-sustained. Using statistical mechanics, we also study the conditions under which the conversion of CO to graphene and carbon dioxide is thermodynamically favorable, both in the presence and in the absence of hydrogen. These results are a first step toward the development of processes for the carbon-mediated partial sequestration and selective oxidation of CO in a hydrogen atmosphere.

Rational computational design of optimal catalytic surfaces

Using calculations from first-principles based on density functional theory, we introduce an innovative concept for the design of catalysts based on the tuning of the surface properties by progressive layering of thin metal films on an oxide support, where the substrate is substantially exploited as an active design element for the tuning of the reactivity of the metallic surface. We demonstrate this idea by studying the adsorption and activation properties of CO2 on Pd and oxide-supported Pd thin films.