Bipolar electrochemical mechanism for the propulsion of catalytic nanomotors in hydrogen peroxide solutions

被引:441
作者
Wang, Yang [1 ]
Hernandez, Rose M. [1 ]
Bartlett, David J., Jr. [1 ]
Bingham, Julia M. [1 ]
Kline, Timothy R. [1 ]
Sen, Ayusman [1 ]
Mallouk, Thomas E. [1 ]
机构
[1] Penn State Univ, Dept Chem, University Pk, PA 16802 USA
关键词
D O I
10.1021/la0615950
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Bimetallic nanorods are propelled in aqueous solutions by the catalytic decomposition of hydrogen peroxide to oxygen and water. Several mechanisms ( interfacial tension gradients, bubble recoil, viscous Brownian ratchet, self-electrophoresis) have been proposed for the transduction of chemical to mechanical energy in this system. From Tafel plots of anodic and cathodic hydrogen peroxide reactions at various metal (Au, Pt, Rh, Ni, Ru, and Pd) ultramicroelectrodes, we determine the potential at which the anodic and cathodic reaction rates are equal for each metal. These measurements allow one to predict the direction of motion of all possible bimetallic combinations according to the bipolar electrochemical (or self-electrophoretic) mechanism. These predictions are consistent with the observed direction of motion in all cases studied, providing strong support for the mechanism. We also find that segmented nanorods with one Au end and one poly(pyrrole) end containing catalase, an enzyme that decomposes hydrogen peroxide nonelectrochemically, perform the overall catalytic reaction at a rate similar to that of nanorods containing Au and Pt segments. However, in this case there is no observed axial movement, again supporting the bipolar electrochemical propulsion mechanism for bimetallic nanorods.
引用
收藏
页码:10451 / 10456
页数:6
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