(509al) Effects of Molecular Properties on Adsorption Energies of Anionic Adsorbates on Platinum

In (electro)catalysis, adsorption or desorption of material on a catalytic surface and the changes in the energy involved, dictate the efficacy of the catalysis. From various scaling relations, we already know that these adsorption energies of a molecule on a specific surface are linearly correlated to that of the atom through which the molecule binds on that surface [1]. But it is yet unknown, for a specific binding atom, which properties of the adsorbate dictate the adsorption energy, and in particular, the intercept of the linear scaling relation. Recent density functional theory calculations (DFT) [2] and experimental measurements in ultra-high vacuum [3] have shown, for example, that the adsorption strength of many alkyl groups (which all bind through C) and of some oxygen-containing molecular fragments (which all bind through O) correlate with how strongly the binding atom (C, O) bond with hydrogen. In this work, we will show how cyclic voltammetry can be used to examine metal-adsorbate adsorption strength in the electrochemical environment, and understand how trends in binding strength between a series of similar anionic adsorbates on a well-defined Pt (111) single crystal electrode correlate with properties of the adsorbates. Results from both experiments and DFT will be compared.

[1] F. Abild-Pedersen, J. Greeley, F. Studt, J. Rossmeisl, T.R. Munter, P.G. Moses, E. Skúlason, T. Bligaard, J.K. Nørskov, Phys. Rev. Lett., 99, 016105 (2007).
[2] M.M. Montemore, J. Will Medlin, J. Chem. Phys., 136, 204710 (2012).
[3] E.M. Karp, T.L. Silbaugh, C.T. Campbell, JACS, 136, 4137 (2014).