Catalytic Thermodynamics of Nanocluster Adsorbates from Informational Statistical Mechanics

Abstract

This letter presents a new approach for studying the catalytic thermodynamics of cuboctahedral nanoclusters, using informational statistical mechanics. The Morse potential determines bond energies between cluster atoms in a coordination type calculation. Applied density functional theory calculations demonstrate adatom effects on the thermodynamic quantities, which are derived from a Hamiltonian. Calculations of the entropy, free energy, and total energy show linear behavior, as the coverage of oxygen on platinum, and hydrogen on palladium, increases from bridge sites on the surface. The data exhibits size effects for the measured thermodynamic properties with cluster diameters between 2 and 5 nm. Entropy and enthalpy calculations of Pt–O2 compare well with previous theoretical data for Pt(111)–O2, and trends for Pd–H are similar to experimental measurements on Pd–H2 nanoclusters. These techniques are applicable to a wide variety of cluster–adsorbate interactions, encouraging further research.