Reversed Janus Micro/Nanomotors with Internal Chemical Engine.
Reversed Janus Micro/Nanomotors with Internal Chemical Engine.
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DOI：
10.1021/acsnano.6b04358
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发表时间：
2016-09-27
期刊：
影响因子：
17.1
通讯作者：
Sánchez S
中科院分区：
文献类型：
--
作者：
Ma X;Jang S;Popescu MN;Uspal WE;Miguel-López A;Hahn K;Kim DP;Sánchez S
自动运动的 Janus 胶体对于实现各种微技术应用以及提高我们对人造微型和纳米游泳者运动机制的理解非常重要。我们在这里展示的微/纳米电机具有内部催化“化学发动机”的反向Janus结构。催化材料（此处为铂 (Pt)）嵌入介孔二氧化硅 (mSiO2) 基中空颗粒的内部，当悬浮在过氧化物 (H2O2) 水溶液中时，会引发 H2O2 分解。非催化 (Pt) 半球上的孔/间隙允许溶液中的化学物质在颗粒的外部和内部之间进行交换。通过改变颗粒的直径，我们观察到尺寸依赖性运动行为，其形式为 500 nm 颗粒的增强扩散，以及 1.5 和 3 μm 颗粒向非金属部分的自泳运动。运动方向通过基于自泳的理论模型合理化。对于 3 μm 颗粒，观察到多孔部分形态的变化，伴随着气泡成核和喷射的推进机制的变化以及运动方向的变化。
Self-motile Janus colloids are important for enabling a wide variety of microtechnology applications as well as for improving our understanding of the mechanisms of motion of artificial micro- and nanoswimmers. We present here micro/nanomotors which possess a reversed Janus structure of an internal catalytic “chemical engine”. The catalytic material (here platinum (Pt)) is embedded within the interior of the mesoporous silica (mSiO2)-based hollow particles and triggers the decomposition of H2O2 when suspended in an aqueous peroxide (H2O2) solution. The pores/gaps at the noncatalytic (Pt) hemisphere allow the exchange of chemical species in solution between the exterior and the interior of the particle. By varying the diameter of the particles, we observed size-dependent motile behavior in the form of enhanced diffusion for 500 nm particles, and self-phoretic motion, toward the nonmetallic part, for 1.5 and 3 μm ones. The direction of motion was rationalized by a theoretical model based on self-phoresis. For the 3 μm particles, a change in the morphology of the porous part is observed, which is accompanied by a change in the mechanism of propulsion via bubble nucleation and ejection as well as a change in the direction of motion.