First-principles calculations of cyanide-modified Pt(111) surfaces

E.P.M. LEIVA

Reisensburg

Workshop; Elementary reaction steps in electrocatalysis: Theory meets Experiment,; 2012

DFG

First-principles calculations of cyanide-modified Pt(111) surfaces aEzequiel P. M. Leiva, MaríaEscudero-Escribanob,Germán J. Soldanoc, Paola Quainod, Martín E. ZoloffMichoffa, Wolfgang Schmicklerc, and ÁngelCuestab aINFIQC, Departamento de Matemática y Física, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, ArgentinabInstituto de Química Física “Rocasolano”, CSIC, C. Serrano, 119, E-28006 Madrid, Spain, cInstitutfürTheoretischeChemie, Universitat Ulm, D-89069 Ulm, Germany, dPRELINE, Facultad de Ingeniería Química, Universidad Nacional del Litoral, 3000, Santa Fe, Argentina.   Cyanide-modified Pt(111) surfaces have been recently used to consider atomic-ensemble effects in electrocatalysis[1,2]. These studies have been based on the assumption that cyanide acts as a third body, blocking some surface sites but leaving the electronic properties of the surrounding ones unaltered, although this is in apparent contradiction with the observation of a positive shift of 0.2 V in the onset of hydrogen adsorption on cyanide-modified Pt(111) electrodes, as compared with clean Pt(111). We have performed theoretical calculations in order to provide support to this assumption and explain the positive shift in the onset of hydrogen adsorption, which appears to be due to the formation of CNHad.  Alkali metal cationscan adsorb on the above mentioned cyanide-modified Pt(111) electrodes,  as has been observed in STM experiments[3]. In the present work we also analyze the energetic stability of different surface structures involving adsorbed cations, and address the problem of their observability by means of scanning tunneling microscopy.   References [1]A. Cuesta, J. Am. Chem. Soc. 128 (2006) 13332. [2]A. Cuesta, M. Escudero, B. Lanova and H. Baltruschat, Langmuir 25 (2009) 6500. [3] M. Escudero-Escribano, M. E. ZoloffMichoff, E. P. M. Leiva, N.M. Marković, C. Gutiérrez, and A. Cuesta, ChemPhysChem, 12 (2011)2230.