The design and fabrication of economically viable anode catalysts for the methanol oxidation reaction (MOR) have been challenging issues in direct methanol fuel cells (DMFCs) over the decades.
Three kinds of tri-metallic catalysts with core–shell structure are synthesized, in which the outer shell is alloy of Pt and Ag, and the inner core consists of Ag and Pd. Amongst, the composite catalyst with atomic ratio of Ag, Pd and Pt equaling to 1:1.4:1.2 (denoted as Ag1Pd1.4Pt1.2) has the greatest total mass activity (3310.7 mA mgmetal
−1), which is much higher than commercial Pt-Ru, Pt- and Pd-based catalysts reported previously. The superior catalytic activity for methanol oxidation should be due to the high amount of Pt alloyed with the least Ag in outer shell and boundary of PtAg outer shell and AgPd inner core composed of tiny nanoclusters, endowing synergistic effect from the electronic structure, numerous defeats, and available great internal and external surface areas. In addition, Ag1Pd1.4Pt1.2 catalyst about 250 nm at mesoscopic scale shows improved stability to large extent. Meanwhile, the presence of Pd in Ag1Pd1.4Pt1.2 contributes outstanding ability against CO poisoning. This work may pave a promising way to prepare core–shell composite catalyst with high catalytic performance for fuel cell application.
The direct methanol fuel cell calls for designing various highly active catalysts containing less platinum, still keeping with reasonable stability. In this work, through controlling reaction system under acidic media (pH = 1), ∼3 nm PtPd nanoparticles are dispersed onto the TiO 2 support ( 3 PtPd/TiO 2 ) via a facile one-pot hydrothermal route. In comparison with that of homemade Pt/TiO 2 and commercial Pt black catalysts, as-synthesized 3 PtPd/TiO 2 shows a better performance for directly electrochemical catalysis of methanol and simultaneously exhibits high ability against poison from carbon oxide species. Clearly, the optimized usage of anatase TiO 2 not only enhances catalytic activity due to the metal-support interactions but also improves long durability, which could be attributed to the OH existing at the surfaces of TiO 2 and Pd.
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