Facile Synthesis of Gold-Nanoparticle-Decorated Gd_0.3Ce_0.7O_1.9 Nanotubes with Enhanced Catalytic Activity for Oxygen Reduction Reaction

We demonstrated a facile method to synthesize gold-nanoparticle-decorated Gd0.3Ce0.7O1.9 (Au-GDC) nanotubes. X-ray diffraction, transmission electron microscopy, X-ray photoelectron microscopy, and energy-dispersive X-ray measurements were performed to characterize their structure and composition. In this unique structure, gold nanoparticles were uniformly decorated in the inner wall of Gd0.3Ce0.7O1.9 (GDC) nanotubes with high gold loading. The catalytic activity of a Au-GDC nanotube catalyst for oxygen reduction reaction (ORR) in a 0.1 M KOH solution was studied using a rotating ring-disk electrode (RRDE) technique. RRDE results show that the ORR mainly favors a direct four-electron pathway, and a maximum cathodic limiting current density of -6.70 mA cm(-2) at 2500 rpm was obtained, which is much bigger than that of gold bulk electrode and as-reported gold/rGO hybrid catalysts and close to the behavior of a commercial Pt/C catalyst below -0.8 V. Most importantly, the as-prepared Au-GDC nanotube catalyst exhibits excellent stability for the ORR because of the maximum interaction between gold nanoparticles and GDC nanotube supports.