Department of Chemical Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
Centro de Fisica Teórica e Computacional, Departamento de Fisica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande P-1749-016, Lisboa, Portugal.
Nat Commun. 2019 Jan 30;10(1):495. doi: 10.1038/s41467-019-08423-7.
The pursuit of chemically-powered colloidal machines requires individual components that perform different motions within a common environment. Such motions can be tailored by controlling the shape and/or composition of catalytic microparticles; however, the ability to design particle motions remains limited by incomplete understanding of the relevant propulsion mechanism(s). Here, we demonstrate that platinum microparticles move spontaneously in solutions of hydrogen peroxide and that their motions can be rationally designed by controlling particle shape. Nanofabricated particles with n-fold rotational symmetry rotate steadily with speed and direction specified by the type and extent of shape asymmetry. The observed relationships between particle shape and motion provide evidence for a self-electrophoretic propulsion mechanism, whereby anodic oxidation and cathodic reduction occur at different rates at different locations on the particle surface. We develop a mathematical model that explains how particle shape impacts the relevant electrocatalytic reactions and the resulting electrokinetic flows that drive particle motion.
追求化学动力胶体机器需要在共同环境中执行不同运动的单个组件。通过控制催化微粒子的形状和/或组成，可以对这些运动进行定制；然而，由于对相关推进机制的理解不完整，设计粒子运动的能力仍然受到限制。在这里，我们证明了铂微粒子在过氧化氢溶液中自发移动，并且可以通过控制粒子形状来合理设计它们的运动。具有 n 重旋转对称性的纳米制造粒子以速度和方向稳定旋转，速度和方向由形状不对称的类型和程度指定。观察到的粒子形状与运动之间的关系为自电泳推进机制提供了证据，其中在粒子表面的不同位置以不同的速率发生阳极氧化和阴极还原。我们开发了一个数学模型，解释了粒子形状如何影响相关的电催化反应以及由此产生的电动流，从而驱动粒子运动。
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