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Abstract: A thin Pt skeleton with a well-defined porous structure prepared on Y2O3–ZrO2 (YSZ) substrate is used as template to study the effect of impregnated pure CeO2 and Gd-doped CeO2 (GDC) nanoparticles on the electrochemical activity of Pt electrodes and to minimize possible interactions between the infiltrated phase/solution and the porous skeleton structure. The results show that the activity of Pt cathodes is enhanced by the infiltration of 0.2mgcm−2 (6.2wt.%) CeO2 and GDC nanoparticles. For the O2 reduction reaction under open circuit and at low current region the promotion effect of infiltrated CeO2 and GDC nanoparticles is close, but under higher currents the infiltrated GDC exhibits a much higher electrocatalytic activity as compared to the infiltrated CeO2 for the O2 reduction reaction on the Pt electrodes. The high electronic conductivity and high oxygen vacancies of GDC nanoparticles under polarization or dc bias, as compared to that of pure CeO2 are most likely responsible for the high catalytic effect of GDC nanoparticles for the O2 reduction reaction on the Pt. This study demonstrates that the electrochemical performance of infiltrated nano-structured electrodes is fundamentally affected by the catalytic properties of infiltrated nanoparticles. [Copyright &y& Elsevier]