Monolayer Nanoislands of Pt on Au and Cu: A First-Principles Computational Study

Au- and Cu-supported Pt monolayer model islands with diameters of up to 2.7 nm were studied by density functional calculations to explore support effects on metal-supported metal nanoislands. We analyzed structure, energy, and reactivity aspects of Pt n monolayer species (n = 19–91) on Au(111) and Cu(111). Exploiting scaling relationships, we were able to quantify lateral and vertical interaction energies in terms of contributions of atoms at the edges and in the inner regions of nanoislands. According to our computational results, the supporting material hardly affects the structure of the Pt nanoislands. This also holds for the catalytic activity, as quantified by the d-band model, because for Au and Cu as supporting metals, the d-band centers of the Pt nanoislands differ on average by ∼0.2 eV only. In contrast, this difference is ∼1 eV for pseudomorphic Pt overlayers, indicating that pseudomorphic model systems do not adequately represent metal-supported metal nanoislands with diameters of a few nanometers. These results are expected to impact the interpretation of experimental and computational studies on metal-supported metal nanoparticles.