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

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.     

Platinum nanoparticles on the antimony-doped tin dioxide surface: Quantum-chemical modeling

The interaction of Pt₂₉ nanoparticles with pristine and reduced (110) and (100) SnO₂ surfaces doped with Sb has been modeled using the density functional theory method within the generalized gradient approximation (GGA). It has been demonstrated that the introduction of antimony contributes to dispersion of substrate particles and, in some cases, leads to an increase in the energy of interaction with platinum and to the fixation of platinum nanoparticles on the surface.     

Oxygen behavior on the platinum surface: A quantum-chemical modeling

The dissociation of molecular oxygen and the migration of O atoms over the (100) and (111) platinum crystal surfaces have been modeled by the density functional theory method within the generalized gradient approximation (GGA). It has been demonstrated that the barrier to dissociation of the dioxygen molecule on the (100) surface is lower than that on the (111) surface. Oxygen atoms migrate over the (100) surface more readily than over the (111) surface. On the basis of these data, it is suggested that the Pt(100) surface is most efficient for dioxygen activation.     

Activation of molecular hydrogen on platinum nanoparticles: Quantum-chemical modeling

The interaction of molecular hydrogen with platinum clusters of different size has been modeled by the density functional theory method within the generalized gradient approximation (GGA). The cluster size turns out to have little effect on the interaction energy, whereas the effect of the cluster structure is rather significant. The most efficient interaction with hydrogen is observed for clusters with a structure resembling the crystal structure of platinum metal. In such clusters, the hydrogen molecule is attached to its surface without a barrier. Configurations with the bidentate hydrogen coordination are the most stable ones. The H atoms can migrate over the cluster surface, overcoming moderate potential barriers of ∼0.3–0.4 eV.     

Application of Grid technology in computational chemistry

The key trends and prospects of development of computational chemistry that formed in the early 2010s are considered. The most advanced methods for solution of various types of challenges in the computational and quantum chemistry by calculations in the distributed environments (Grid) and on high-performance supercomputer installations and the application methods of parallel and distributed computations are demonstrated; the tailor-made technologies developed for these calculations are described.