2, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Subnanometer transition metal clusters have recieved significant attention as promising materials for catalysis, particularly over their bulk counterparts. The electronic structure of the exposed metal sites can vary significantly with atomic size and geometry, which presents the opprotunity to design metal clusters of a specific atomic size and composition for the desired catalytic application. One such application is towards methane conversion, which requires suitable catalysts to promote the activation of its strong C-H bond. Using density functional theory, we investigate a selection of promising transition metal clusters and identify promising candidates based on strong methane adsorption and low C-H activation barriers. Our results conclude that facile C-H activation is closely related to the ability of the metal sites to complex with the methane molecule. We further show that these methane activation properties are extremely size, geometry and composition dependent, with significant implications for eventual experimental applications. These studies provide the first step in designing realistic metal cluster catalysts for methane conversion.