发表机构
Istituto di BioRobotica-Scuola Superiore Sant’Anna; Wageningen University & Research; Center for Materials Interfaces, Electron Crystallography, Italian Institute of Technology（机器人研究所圣安娜高等学院; 瓦赫宁根大学与研究; 意大利理工学院材料界面与电子晶体学中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出用含球形凹槽的图案化基底制备Janus主动粒子，可调控铂厚度对比度、抑制Pt桥，在2.5% H₂O₂中提升推进效率，间接支持自电泳为主动粒子主要推进机制。
AI 中文摘要
半包覆铂（Pt）的惰性胶体是化学驱动主动粒子的标准模型，但其实验上难以剖析其在过氧化氢（H₂O₂）中推进的微观起源。此前自扩散电泳是主流理论，近期则提出自电泳才是主要推进机制：根据该机制，定向金属沉积产生的极-赤道Pt厚度梯度足以在金属帽上形成阳极和阴极区域，进而由H₂O₂分解维持电场。要提升这类粒子的自推进性能，需精确控制Pt厚度分布，但当前标准方法（如蒸发或溅射）无法实现。本文提出一种制备Janus主动粒子的方法：将二氧化硅微球组装在含球形凹槽的图案化基底上，凹槽的深度和间距可调控粒子包覆程度，同时抑制邻近缺陷（Pt桥）。通过聚焦离子束截面验证，所得粒子具有可调的铂厚度对比度。在2.5% H₂O₂中，结果显示该控制可显著提升推进效率，间接支持自电泳为主要机制的假设。这些结果表明，图案化基底路线可增强对催化剂沉积的控制，实现新型Janus形貌，为主动胶体的更精确工程设计提供可能。
英文摘要
Inert colloids half-coated with platinum (Pt) are a standard model of chemically powered active particles, yet the microscopic origins of their propulsion in hydrogen peroxide (H2O2) remain difficult to dissect experimentally. Whereas self-diffusiophoresis was the prevailing theory, self-electrophoresis has been more recently suggested as the main mechanism of propulsion. According to the latter mechanism, the pole-to-equator Pt-thickness gradient produced by directional metal deposition is sufficient to create anodic and cathodic regions on the metal cap and thereby generate an electric field sustained by H2O2 decomposition. Enhancing self-propulsion performance of such particles thus requires precise control over the Pt thickness distribution, which is currently not achievable with standard methods (e.g. evaporation or sputtering). Here, we propose a method to fabricate Janus active particles by assembling silica microspheres on patterned substrates containing spherical grooves whose depth and spacing set the degree of particle coating while simultaneously suppressing proximity-led defects (Pt bridges). The resulting particles exhibit a tunable platinum-thickness contrast, as verified by Focused-Ion-Beam cross-sections. In 2.5% H2O2, our results suggest that this control can significantly increase propulsion efficiency, while providing evidence indirectly supporting the hypothesis that self-electrophoresis is the dominant mechanism. These results demonstrate that our patterned-substrate route can enhance control over the catalyst deposition and enable novel Janus morphologies, allowing for more precise engineering of active colloids.
