Synergetic Effect of SiO 2 and CeO 2 as the Noncarbon Composite Support on Significantly Promoting Methanol Oxidation and Oxygen Reduction Reaction

Pt/C, as the commonly used electrocatalyst in direct methanol fuel cells, suffers from the difficulty of easy corrosion of the carbon support, which results in a poor catalyst durability in the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) processes. The SiO 2 –CeO 2 composite oxide is explored as the noncarbon support to load the PtCu catalyst. PtCu/SiO 2 –CeO 2 with the nanotube morphology exhibited a specific activity (SA) 10.55 times higher than that of Pt/C toward MOR and an SA 3.33 times higher than that of Pt/C toward ORR. Moreover, PtCu/SiO 2 –CeO 2 shows excellent ORR durability, and the activity became even better after 50,000 cycles. The high performance is due to the synergetic effect of SiO 2 and CeO 2 . CeO 2 causes an impurity level within SiO 2 , which alters the electronic structure and the interaction with PtCu. On the other hand, SiO 2 imposes a confinement effect on CeO 2 and prevents the aggregation of CeO 2 nanoparticles which bind PtCu strongly. The density functional theory calculations reveal that the OOH* adsorption of the PtCu/SiO 2 –CeO 2 structure is further enhanced under the synergistic action, leading to a lower overpotential.