(750e) Morphological, Electronic, and Catalytic Properties of Graphene-Supported Pt Nanoclusters
Graphene has received considerable recent attention as a support material for fuel-cell electrodes due to its high surface area and excellent electrical conductivity. Experiments indicate that graphene-supported Pt nanoparticles exhibit greater stability and better electrocatalytic activity as compared to their counterparts on traditional carbon supports, or even bulk Pt electrodes.
In this study we use a combination of empirical-potential molecular-dynamics calculations and first-principles density functional theory calculations to investigate the structural, electronic, and catalytic properties of Pt nanoclusters on graphene supports. We present detailed thermodynamic and electronic structure analyses of Pt clusters on both defective and defect-free graphene substrates and elucidate the role of support point defects in altering the electronic structure of the supported clusters. Defects in graphene supports are found to enhance the metal-support interaction thereby increasing stability towards catalyst sintering. The strong Pt-C interactions are also accompanied by significant charge redistribution between the cluster and the substrate, which alters the catalytic properties of the cluster.
As a model reaction, we investigate CO adsorption and oxidation on graphene-supported Pt clusters. We show that clusters bound to defects in graphene could potentially exhibit increased tolerance toward CO poisoning. We examine the activity of the graphene-supported Pt clusters for the CO oxidation reaction and obtain estimates for CO-oxidation kinetics. Reaction kinetics on supported Pt nanoclusters are comparable with bulk Pt and, on average, faster than on unsupported clusters.
Overall, our results suggest promising avenues for controlling the dispersion and catalytic activity of Pt nanoclusters on graphene supports via defect engineering.