Symmetric growth of Pt ultrathin nanowires from dumbbell nuclei for use as oxygen reduction catalysts

This work demonstrates the synthesis of Pt ultrathin nanowires assisted by chromium hexacarbonyl [Cr(CO)(6)]. The nanowires exhibit a uniform diameter of 2-3 nm. The length can reach up to several microns. It was found that Cr species produced dumbbell-like nuclei which play a pivotal role in the formation of the Pt nanowires. Such Pt nanowires can be tuned to nanocubes by simply decreasing the concentration of [Cr(CO)(6)]. Compared to a commercial Pt/C catalyst (45 wt%, Vulcan, Tanaka) and Pt black (fuel cell grade, Sigma), the synthesized Pt nanowires exhibit superior performance in electrocatalytic oxygen reduction with a specific activity of 0.368 mA/cm(2), which was 2.7 and 1.8 times greater than that of Pt/C (0.138 mA/cm(2)) and Pt black (0.202 mA/cm(2)), respectively. The mass activity of Pt nanowires (0.088 mA/mu g) is 2.3 times that of Pt black (0.038 mA/mu g) and comparable to that of Pt/C (0.085 mA/mu g).