Ambient Synthesis of High-Quality Ruthenium Nanowires and the Morphology-Dependent Electrocatalytic Performance of Platinum-Decorated Ruthenium Nanowires and Nanoparticles in the Methanol Oxidation Reaction

We report for the first time (a) the synthesis of elemental ruthenium nanowires (Ru NWs), (b) a method for modifying their surfaces with platinum (Pt), and (c) the morphology-dependent methanol oxidation reaction (MOR) performance of high-quality Pt-modified Ru NW electrocatalysts. The synthesis of our elemental Ru NWs has been accomplished utilizing a template-based method under ambient conditions. As-prepared Ru NWs are crystalline and elementally pure, maintain electrochemical properties analogous to elemental Ru, and can be generated with average diameters ranging from 44 to 280 nm. We rationally examine the morphology-dependent performance of the Ru NWs by comparison with commercial Ru nanoparticle (NP)/carbon (C) systems after decorating the surfaces of these structures with Pt. We have demonstrated that the deposition of Pt onto the Ru NWs (Pt~Ru NWs) results in a unique hierarchical structure, wherein the deposited Pt exists as discrete clusters on the surface. By contrast, we find that the Pt-decorated commercial Ru NP/C (Pt~Ru NP/C) results in the formation of an alloy-type NP. The Pt~Ru NPs (0.61 A/mg of Pt) possess nearly 2-fold higher Pt mass activity than analogous Pt~Ru NW electrocatalysts (0.36 A/mg of Pt). On the basis of a long-term durability test, it is apparent that both catalysts undergo significant declines in performance, potentially resulting from aggregation and ripening in the case of Pt~Ru NP/C and the effects of catalyst poisoning in the Pt~Ru NWs. At the conclusion of the test, both catalysts maintain comparable performance, despite a slightly enhanced performance in Pt~Ru NP/C. In addition, the measured mass-normalized MOR activity of the Pt~Ru NWs (0.36 A/mg of Pt) was significantly enhanced as compared with supported elemental Pt (Pt NP/C, 0.09 A/mg of Pt) and alloy-type PtRu (PtRu NP/C, 0.24 A/mg of Pt) NPs, both serving as commercial standards.