Recent developments in the rapid screening of electro-catalysts and a new representation of their activity

Recent developments in the rapid screening of electrocatalysts and a new representation of their activity Alessandro Minguzzia, Dario Battistelb, Cristina Locatellia, Joaquin Rodriguez Lopezc, Alberto Vertovaa, Salvatore Danieleb, Sandra Rondininia, Allen J. Bardc aDipartimento di Chimica Fisica ed Elettrochimica, Università degli Studi di Milano,, Via Golgi 19, I-20147 Milano alessandro.minguzzi@unimi.it bDipartimento di Chimica Fisica, Università “Ca’ Foscari”di Venezia, Calle Larga, S. Marta 2137, I-30123 Venezia cCenter for Electrochemistry, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA Scanning electrochemical microscopy (SECM) is an innovative technique, whose wide range of applicability is continuously expanding thanks to the development of new instrumental modes of operation. The possibility of scanning a movable microelectrode over the surface under investigation is the first among its several attractive features. Next, the nature of the substrate can span a wide range from biological systems to electrocatalytic surfaces, from photoactive materials to nanostructured textures, thus making the technique extremely flexible. In recent years, SECM has been applied to the study of libraries of materials useful as electrocatalysts or photoelectrocatalysts in energy conversion devices1-3. In this work, recent results on the rapid screening of the electrochemical activity of material libraries for the oxygen evolution or the oxygen reduction reactions have been demonstrated and discussed. The investigation is carried out on model mixtures based on the IrOx systems, which are promising materials for the preparation of operational devices. The effectiveness of the developed methods is supported by digital simulations. Experimental results obtained by SECM are confirmed by voltammetric and physico-chemical techniques. In parallel, a new type of 3-D diagram reporting the activity as a function of the applied potential and the pH (a dynamic potential-pH diagram) is proposed. Thanks to the use of a colour code, these diagrams enable the immediate comparison of different electrocatalytic materials for the same reaction, over a broad range of experimental conditions. 1. J.L Férnandez, D. A Walsh, A.J.Bard, J. Am. Chem. Soc. 2005, 127, 357-365 2. A.Minguzzi, M. A. Apulche-Aviles, J.Rodriguez Lopez, S.Rondinini, A.J. Bard, Anal. Chem. 2008, 80, 4055. 3 J.Lee, H.Ye, S.Pan, A. J.Bard, Anal. Chem. 2008, 80, 7445