Dr. Maria Escudero-Escribano
200-305, Lane History Corner, Main Quad
Abstract
Proton exchange membrane fuel cells (PEMFCs) are potentially zero emission sources of power, which are expected to play a key role in a future societybased on sustainable energy. However, appreciable loadings of Pt-based catalysts are needed to drive the oxygen reduction reaction. In order to improve the reaction kinetics and reduce the Pt loading, we need to develop more efficient catalysts. This can be achieved by modification of the geometric structure (atomic ensembleeffects1) and/or alteration of the electronic properties of the surface atoms (electronic effects2,3).
First, I will address atomic ensemble effects in electrocatalysis. We have used a self-ordered molecular pattern, cyanide-modified Pt(111),[CN-Pt(111)] to study the oxygen reduction1. CN groups form an ordered structurethat blocks all the three-fold hollow sites, effectively blocking the adsorption of spectator anionsin the electrolyte, such as sulphate and phosphate. Nonetheless, the holes in this ordered structure are sufficiently large to allow the adsorption of reaction oxygenmolecules. As a consequence, CN-Pt(111) presents a 25-fold enhancement overPt(111)1.
References
1 D. Strmcnik, M. Escudero-Escribano, K. Kodama, V. R. Stamenkovic, A. Cuesta, N. Markovic, Nature Chem.
2010, 2, 880.
2 M. Escudero-Escribano, A. Verdaguer-Casadevall, P. Malacrida, U. Grønbjerg, B.P. Knudsen, A.K. Jepsen, J. Rossmeisl, I.E.L. Stephens, I. Chorkendorff, J. Am. Chem. Soc. 2012, 130, 16476.
3 M. Escudero-Escribano*, P. Malacrida, M.H. Hansen, U.G. Vej-Hansen, A. Velázquez-Palenzuela, V. Tripkovic, J. Schiøtz,J. Rossmeisl, I.E.L.Stephens*, I. Chorkendorff*, Science 2016, 352, 73.