Trends in the electrocatalytic activity of nanostructures of Pd on Au(111) electrodes

PAOLA QUAINO; KAY POETTING; ELISABETH SANTOS; WOLFGANG SCHMICKLER

Krakow

Congreso; 7th Spring Meeting of the International Society of Electrochemistry; 2009

The International Society of Electrochemistry - ISE

The electrocatalytic properties of an electrode depend not only on the composition, but also on the structure. It is well known that the nanostructured materials show different activities than bulk materials. This nanosize effect has been attributed to changes in electronic properties. An interesting case is Au(111) modified by adsorbed layers of palladium. Experimental results show that the rate of hydrogen evolution increases with decreasing numbers of Pd layers on Au(111), and it is considerably higher for sub-monolayers. Qualitative explanations based on the position of the center of the d-band have been proposed by the authors. However, there is a lack of the theoretical foundations to explain these observations, and the phenomenon remains not well understood.In this context, the purpose of our work is to explain the variation of the rate with the structure of the electrode. For this, we apply a formalism developed by two of us, in which the Hueckel theory is used to describe the bonding of the molecule and DFT results are used only to obtain the dband structures of the substrates. These data were fitted with a set of three semielliptical functions in order to have analytical expressions for the chemisorption functions.Our preliminary results show that the role of the interactions of molecule with the electrocatalyst in the electrochemical environment  including solvent effects and potential are crucial to explain the different activities of different materials and surface structures.