Some Considerations on Underpotential Deposition on Free Nanoparticles

O. A. OVIEDO, C. F. A. NEGRE, M. M. MARISCAL, C. G. SÁNCHEZ AND E.P. M. LEIVA

Congreso; 11th Spring Meeting of the International Society of Electrochemistry; 2012

Electrosorption of metal ions on foreign substrates at potentials more positive than the reversible Nernst deposition potential, known as underpotential deposition (upd), allows surface control of metal coverage by straightforward application of a potential difference. The possibility of using upd to control the shape of Au-NPs has been recently explored by Personik et al. [1] but recent experiments developed by Compton and co-workers [2] show that remarkable size effects occur when nanoparticle size is reduced below 50 nm, where the upd phenomenon seems to vanish. Such a curious transition from upd to overpotential deposition has also been predicted by calculations [3,4]. In the present work, we report on recent advances in the theoretical modeling of upd on free NPs [5,6]. We discuss this problem on basic of tree different framework: 1) theoretical approach: from nanothermodinamic formalism up to statistical mechanical model; 2) atomistic simulations approach: using many simulation techniques, from simple gas models type up to continuous simulationlike full grand canonical Monte Carlo; 3) the experimental feasibility: by means of a state-of-the art quantum mechanical atomistic model, we simulated their plasmon spectra in different conditions, even at room temperature. We discuss the electrochemical decoration of Au, Ag and Pd nanoparticles by different foreign metals. It is found that depending on precursor nanoparticle size and shape, controlled decoration may be achieved in undersaturation or oversaturation conditions. Multilayer deposition is also considered, with the finding that this phenomenon is also size dependent in perfect harmony with experimental measurements.   [1] M.L. Personick, M.R. Langille, J. Zhang, and C.A. Mirkin, Nano Lett. 11 (2011) 3394. [2] F.W. Campbell, Y. Zhou and R.G. Compton, New Journal of Chemistry, 34, (2010), 187. F.W. Campbell and R.G. Compton, Int. J. Electrochem. Sci., 5 (2010) 407. Y. Zhou, N.V. Rees, and R.G. Compton, ChemPhysChem, 12, (2011), 2085. [3] O. A. Oviedo, E. P. M. Leiva and M. M. Mariscal, Phys. Chem. Chem. Phys., 10 (2008) 3561. [4] O. A. Oviedo, M. M. Mariscal and E. P. M. Leiva. Phys. Chem. Chem. Phys. 12 (2010) 4580. [5] O.A. Oviedo, C.F.A. Negre, M.M. Mariscal, C.G. Sánchez, E.P.M. Leiva. Electrochemistry Communications 16 (2012) 1-5. [6] “Metal Clusters and Nanoalloys: From Modeling to Applications”, Nanostructure Science and Technology. Springer. ISBN 978-1-4614-3267-82012. In press.