Improving the adsorption of Au atoms and nanoparticles on graphite via Li intercalation

Supported nanoclusters have an important future in chemical processes such as catalysis. However, to optimize the properties of supported nanoclusters, attention must be paid to the electronic properties of both adsorbate and substrate materials. Highly ordered pyrolytic graphite is commonly used as a substrate for Au nanoclusters; however, cluster functionality and mobility is a problem on this inert surface. Therefore, we have designed a model for Li-doped graphite and investigated the electronic properties of adsorbed Au atoms and nanoclusters on this material using density functional theory (DFT). We find that increasing the concentration of Li atoms in the substrate results in improved adsorption for both Au atoms and Au16 nanoclusters onto the surface, with adsorption energies up to 0.96 and 1.50 eV, respectively, when using the Perdew, Burke, and Ernzerhof (PBE) exchange-correlation functional. In the case of the Au16 nanocluster, charge transfer of >1 e is computed, which should make this supported system functionally suitable for reactions such as CO oxidation. Furthermore, a pseudoionic bond is observed in some cases for atomic Au over a surface C atom, though the presence of such chemical interaction is dependent on the exchange-correlation functional used