One-Step Reverse Microemulsion Synthesis of Pt-CeO2/C Catalysts with Improved Nanomorphology and Their Effect on Methanol Electrooxidation Reaction

Pt-CeO2/C catalysts have been synthesized by a one-step reverse microemulsion (RME) method and compared with Pt-CeO2/C prepared by conventional borohydride reduction (CBR) method. The Pt and CeO2 contents in both the synthesized samples are close to the nominal values. Scanning transmission electron microscopic (STEM) images with energy dispersive spectroscopic (EDS) elemental mapping analysis reveal that the Pt-CeO2/C sample prepared by the RME method has a homogeneous distribution of Pt and CeO2 with an intimate contact between the Pt and CeO2 nanoparticles, whereas the Pt-CeO2/C sample prepared by the CBR method consists of large aggregations of Pt and CeO2. The advantage of the improved nanoparticle morphology of the RME samples is manifested in higher catalytic activity for methanol oxidation reaction (MOR). The RME samples exhibit higher mass and specific activities for MOR, compared with the CBR samples. An analysis of the effect of Pt/CeO2 ratio on the MOR activity indicates that the Pt-CeO2/C sample with 40 wt % of CeO2 shows a higher catalytic activity than the 30 or 50 wt % samples. A comparison of the durability of the catalysts by accelerated durability tests (ADT) using cyclic voltammetry scanned for 100 cycles between 100 and 1250 mV at a scan rate of 50 mV/s reveals that the Pt-CeO2/C catalysts prepared by the RME method show higher durability than commercial Pt/C.