OP-II-3

PP-III-68Using the proposed model we have found thermodynamically equilibrium shapeof Pt NP located on an abstract support with the same lattice. Parameter values forPt-Pt interactions were taken from work [4]. These data were used in manysimulation researches and proved to be enough realistic. Interactions between NPand support were fitted to make particle shape matching to TEM images.For obtained nanoparticles Monte Carlo simulations of carbon monoxide (CO)adsorption-desorption processes were performed. Seven adsorption site types wereconsidered in simulations: atop, bridge, fcc-hollow and hcp-hollow on (111) face;atop, bridge and hollow on (100) face. CO adsorption energies were taken from [5-6]where they were obtained from DFT simulations. To investigate an influence ofspillover effect on NP coverage we introduced atop adsorption sites on supportsurface. Diffusion of adsorbed CO molecules was fast enough fast to equilibratedistribution over surface and particle either in case of infinitely far diffusion steps or incase of diffusion steps limited by nearest neighbors. To the best of our knowledgethere is no report about computer simulation researches which takes into accountseveral adsorption site types on different NP faces and possible spillover effect.We performed simulations for different values of external chemical potential andadsorption energy of CO on support and measured equilibrium coverage of simulatedNP. On the addressed range of CO-support adsorption energy (from -2,04 eV to -1,5eV) we did not find significant influence of spillover effect on equilibrium NPcoverage. We suppose that in a framework of the model this effect can not berevealed, due to stochastic nature of the employed method which is not able toproperly consider direction of CO flows between NP, support and externalenvironment. Apparently, introduction of reaction on NP or support surface canreveal diffusion of CO molecules between them and show role of spillover effect insuch reactions.References[1]. C.G. Vayenas et al, “Promotion, Electrochemical Promotion, and Metal–Support Interactions: TheUnifying Role of Spillover” in “Catalysis and Electrocatalysis at Nanoparticle Surfaces”, MarcelDekker, New York, 2003.[2]. M. Borowko, “Adsorption on Heterogeneous Surfaces” in “Adsorption Theory, Modeling, andAnalysis”, Marcel Dekker, New York, 2001.[3]. H.-T. Chen, J. Comput. Chem. 2009, 31, 258–265.[4]. F. Cleri, V. Rosato, Phys. Rev. B 1993, 48 22–33.[5]. H. Orita, N. Itoh, Y. Inada, Chem. Phys. Lett. 2004, 384, 271–276.[6]. S. Yamagishi, T. Fujimoto, Y. Inada, H. Orita, J. Phys. Chem. B 2005, 109, 8899–8908.566