Activation energy of hydrogen migration by relay in the O2/Pt19/SnO2/H2 + n H2O system

Abstract

In the framework of investigation of active and stable electrocatalysts for fuel cells, the hydrogen migration by relay with the consecutive formation of H2O molecules in the O2/Pt19/SnO2/H2·nH2O → O/Pt19/SnO2·nH2O + H2O system was simulated. The simulations were performed by the density functional theory (DFT) method with the generalized gradient adjustment (GGA=PBE) under periodic boundary conditions in the projector augmented plane wave (PAW) basis set with a pseudo-potential using the VASP program package. At the cathode on the platinum cluster surface, the oxygen molecules without a barrier form peroxide complexes that dissociate with an energy decrease. The protons transferred via the proton-conducting channels from the anode to cathode form first OH groups bound to the platinum cluster and then H2O molecules that are easily separated from the cluster (∼0.2 eV). The proton transfer process proceeds by relay and involves several water molecules.