Small Angle X-Ray Scattering Study for Investigating the 3D Packing Structure of Pt Catalysts on Gd-Doped CeO2 Supports for Fuel Cells

Abstract

A 3D structural model for fuel cell catalysis systems is constructed, which consist primarily of Pt and CeO2 nanoparticles, to fit observed small angle X-ray scattering (SAXS) patterns by using the reverse Monte–Carlo (RMC) method. The observed SAXS patterns are well reproduced by those of the simulations. Pore size distributions using the obtained structure models are compared with the Barrett–Joyner–Halenda (BJH) analysis for the nitrogen gas adsorption data, and the lower quartiles and medians of the pore diameters are reasonably consistent. In addition, analysis of the SAXS patterns indicates that the number of nanometer-size Pt particles is much smaller than that of the introduced amount. This suggests that most Pt particles are not uniformly distributed in the catalysis system.