Abstract
In this study, antimony-doped tin oxide (ATO) support materials for a Pt anode catalyst in direct methanol fuel cells were prepared and electrochemically evaluated. When the heating temperature was increased from 300 to 400 °C, the ATO samples exhibited a slightly decreased specific surface area and increased electrical conductivity. In particular, the ATO sample heated at 350 °C in an air atmosphere showed improved electrical conductivity (1.3 S cm−1) with an optimum specific surface area of ~34 m2 g−1. The supported Pt catalysts were synthesized using a polyol process with as-prepared and heated ATO samples and Vulcan XC-72R as supports (denoted as Pt/ATO, Pt/ATO-350, and Pt/C, respectively). In the methanol oxidation reaction (MOR), compared to Pt/C and Pt/ATO, Pt/ATO-350 exhibited the best electrocatalytic activity and stability for MOR, which could be attributed to Pt nanoparticles on the relatively stable oxide support with high electrical conductivity and interaction between the Pt catalyst and the heated ATO support.
Highlights
Direct methanol fuel cells (DMFCs) have attracted attention due to the ease of storage and transport of methanol as a liquid fuel and its high energy density, as well as the simplicity of the system for various applications from portable devices to vehicle power sources [1,2,3,4]
Compared to literature, in this study, we found that the electrocatalytic performance of the catalysts for the methanol oxidation reaction (MOR) could be attributed to Pt nanoparticles on the relatively stable oxide support with electrical conductivity and interaction between the Pt catalyst and the antimony-doped tin oxide (ATO) support heated at a varying temperature [31,32,33]
All the samples exhibited the main characteristic peaks corresponding to the (110), (101), (200), and (211) planes at 26◦, 34◦, 38◦, and 52◦, respectively, in a tetragonal SnO2 structure with a = b = 4.74 Å and c = 3.19 Å (P42/mn(136) group, Powder Diffraction File (PDF) 88-0287) [24,29]. This demonstrated that the heated samples maintained a crystal structure identical to that of the ATO before heating, without other phases
Summary
Direct methanol fuel cells (DMFCs) have attracted attention due to the ease of storage and transport of methanol as a liquid fuel and its high energy density, as well as the simplicity of the system for various applications from portable devices to vehicle power sources [1,2,3,4]. The essential characteristics of these supporting materials are high specific surface area to support the nano-sized Pt nanoparticles, high electrical conductivity for efficient electron transport in electrochemical reactions, electrochemical stability, and porous structure to effectively transport product and by-products [12,16,17,18]. Carbon nanostructured materials, such as carbon black, carbon nanotubes, carbon nanofibers, graphene, and graphite nanosheets, have been extensively utilized as supports [9,16,19]. The oxidation of carbon-based materials as a degradation mechanism of the electrocatalyst (Equation (1)) needs to be prevented in order to improve
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