Electronic and magnetic factors in the design of optimum catalysts for hydrogen fuel cells

Abstract

Fuel cells represent one of the most promising energy storage system nowadays. Nonetheless, several obstacles need to be overcome in order to commercially exploit this technology. One of them lies in the efficiency loss due to the overpotential of the oxygen reduction reaction (ORR). Thus, during the last decades, researchers have mainly focused on finding optimum solid catalyst(s) with the following profile: good ORR activity, good stability under the operating FC conditions, inexpensive, widely available and environmentally friendly. Magnetic catalysts, based on 3d-metals such as Pt-based alloys fit conveniently that profile. The understanding of their outstanding catalytic properties starts with the comprehension of complex physicochemical phenomena in which the spins of the electrons play a significant role. Cooperative ferromagnetic spin-electron interactions are indeed one of the most important energetic contributions in allowing milder chemisorption of reactants onto magnetic catalysts. Accordingly, their study is the focus of this doctoral thesis.