Novel Nanocomposite Pt/RuO₂⋅x H₂O/Carbon Nanotube Catalysts for Direct Methanol Fuel Cells

Abstract

Two key problems inhibiting the commercialization of direct methanol fuel cells (DMFCs) are the cost of the precious metals employed and the sluggish kinetics and catalyst poisoning by CO or CHO species. Research to solve the first drawback [1][2][3][4] focuses on the reduction of precious metal loading, which is achieved by increasing the catalysts specific surface area and its accessibility. For the second problem, advanced electrocatalyst design relies on the "bifunctional approach", [5][6][7][8][9][10] in which a second compound such as ruthenium or RuO 2 ·x H 2 O assists the oxidation of CO or CHO species by adsorption of oxygen-containing species close to the poisoned Pt sites. In contrast to previous work on PtRu alloy catalysts, [11][12][13] Rolison and co-workers [14,15] emphasized the importance of hydrous ruthenium oxides because the RuO 2 ·x H 2 O speciation of Ru in nanoscale PtRu blacks shows both high electron and proton conductivity, which results in a much more active catalyst for methanol oxidation. However, direct evidence of the catalytic function of hydrous oxides is very scarce.Mixed proton-electron conducting materials should be ideal catalyst supports for DMFCs since they allow for low ohmic resistance in both the proton and electron conduction at the same time. As hydrous ruthenium(IV) oxide has been reported to contain liquid or liquid-like regions of water to

Rapid Microwave Synthesis of CO Tolerant Reduced Graphene Oxide-Supported Platinum Electrocatalysts for Oxidation of Methanol

“…Hence, the oxygen defect sites play a major role in removing the carbonaceous species and contribute to the low catalyst poisoning on the Pt/RGO hybrids, in a way similar to that found in Pt/RuO 2 and Pt/Ru/MoO x systems. 14,31,32 Figure S6 in the Supporting Information presents the same dependence as that presented in Figure 5a for a complete series of scan rates ranging from 20 to 200 mV/s. It is clear that, at all scan rates ( Figure S6 in the Supporting Information), the three Pt/RGOs exhibit the same general trend electrodes, displaying much higher I f /I b ratios compared to that of Pt/C, indicating superior antipoisoning behavior.…”

Enhanced activity and stability of Pt/C fuel cell anodes by the modification with ruthenium-oxide nanosheets

“…The ligand effect assumes that the energy level of the metal catalyst is modified so that the binding strength with the metal and adsorbed CO is weakened, resulting in a reduction in overpotential for CO oxidation. The possibility that some nanostructured ruthenium oxides (expressed as RuO x H y or RuO 2 •xH 2 O in the literature) may act as co-catalysts has attracted interest and debate [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Several studies have suggested that the binary PtRu alloy structure is not a prerequisite for obtaining the highest activity, and partially oxidized ruthenium species (RuO x ) that are present in the PtRu/C catalysts may contribute to the anodic activity [4][5][6].…”

“…Several studies have suggested that the binary PtRu alloy structure is not a prerequisite for obtaining the highest activity, and partially oxidized ruthenium species (RuO x ) that are present in the PtRu/C catalysts may contribute to the anodic activity [4][5][6]. Enhancement in methanol oxidation activity has been reported for Pt-RuO 2 composite catalysts although the activity of such material is in general lower than that of PtRu alloy [7][8][9][10][11][12][13][14]. On the contrary, other studies have reported that ruthenium oxide is inactive for CO oxidation [15][16][17][18].…”

Carbon Nanotubes and Carbon Nanotubes/Metal Oxide Heterostructures: Synthesis, Characterization and Electrochemical Property

“…Cao et al modified CNTs with surfactants such as sodium dodecylsulfate (SDS) [173]. The hydrophobic aliphatic chain interacted with the surface of the CNTs, while the hydrophilic end attracted the metal ions of the RuCl 3 precursor, which then reacted to form RuO 2 .…”