Carbon supported Pt-Y2O3 and Pt-Gd2O3 nanoparticles prepared via carbonyl chemical route towards oxygen reduction reaction: Kinetics and stability

Abstract

The Pt-M2O3/C (M = Y and Gd) catalysts were synthesized via carbonyl chemical route, and heat-treated at 300 °C. Both catalysts are nanoparticulated with a face-centered cubic (fcc) structure with no secondary phase present as revealed by X-ray diffraction (XRD) patterns similar to Pt/C, generated in the same way. Data analyses of Pt-M2O3/C XRD patterns via the Williamson–Hall method were performed. The stacking fault, and micro-strain values increased with respect to Pt/C catalyst. The transmission electron microscopy (TEM) further revealed that nano-particles are homogeneously dispersed in both Pt/C and Pt-M2O3/C (M = Y and Gd). The mean particle size is close, ca. 3.4 nm for Pt/C, ca. 4.1 nm for Pt-Y2O3/C and ca. 3.6 nm for Pt-Gd2O3/C sample. Although the surface electrochemical studies (cyclic and CO-stripping voltammograms) showed similar Pt surface behavior, the kinetics of oxygen reduction reaction (ORR) on Pt-M2O3/C (M = Y and Gd) catalysts was higher than the homemade Pt/C and commercial Pt/C catalysts (20 wt. %, Johnson Matthey). After 6000 potential cycles (0.6–1.0 V vs. RHE) of accelerated stability test (AST), the remaining Pt active surface (based on hydrogen underpotential deposition region) and kinetic current density (at 0.9 V vs. RHE) in Pt-M2O3/C (M = Y and Gd) catalysts were higher than the reference Pt/C, and commercial Pt/C catalysts. These findings assess the positive effect of M2O3 (M = Y and Gd) in improving the activity and stability of Pt NPs towards ORR.