Pd Nanoparticle Size Effect of Anodic Catalysts on Direct Formic Acid Fuel Cell Initial Performance: Development of a Mathematical Model and Comparison with Experimental Results

Abstract

AbstractDirect Formic Acid Fuel Cell (DFAFC) is considered as a promising liquid fuel cell. Here, the effect of palladium particle size (dPd) of anodic DFAFC catalysts on initial power density was studied. The number of electrochemically available Pd atoms on the surface of Pd nanocrystallites in the anodes were determined experimentally. The cathode potential as a function of the current density has been measured. The mathematical model describing the effect of dPd on DFAFC performance has been developed. It was assumed that: (i) Pd crystallites have shape of cuboctahedron, (ii) Pd atoms lying on edges and corners are inactive, (iii) The activity of Pd atoms lying on crystallite (111) and (100) facets do not change with dPd. The mathematical model describes well the effect of current density and dPd on fuel cell voltage and power density. The model predicts that maximum power density is reached at dPd=2.4 nm.