With the development of surface and interface science and technology, methods for the online modulation of interfacial performance by external stimuli are in high demand. Switching between ultra-low and high friction states is a particular goal owing to its applicability to the development of precision machines and nano/micro-electromechanical systems. In this study, reversible switching between superlubricity and high friction is realized by controlling the electric potential of a gold surface in aqueous salt solution sliding against a SiO2 microsphere. Applying positive potential results creates an ice-like water layer with high hydrogen bonding and adhesion at the interface, leading to nonlinear high friction. However, applying negative potential results in free water on the gold surface and negligible adhesion at the interface, causing linear ultra-low friction (friction coefficient of about 0.004, superlubricity state). A quantitative description of how the external load and interfacial adhesion affected friction force was developed, which agrees well with the experimental results. Thus, this work quantitatively reveals the mechanism of potential-controlled switching between superlubricity and high-friction states. Controlling the interfacial behavior via the electric potential could inspire novel design strategies for nano/micro-electromechanical and nano/micro-fluidic systems.

随着表面和界面科学技术的发展，迫切需要通过外部刺激在线调节界面性能的方法。由于其适用于精密机器和纳米/微机电系统的开发，因此在超低摩擦状态和高摩擦状态之间切换是一个特殊的目标。在这项研究中，通过控制在SiO2微球上滑动的盐水溶液中金表面的电势，可以实现超润滑性与高摩擦力之间的可逆转换。施加正电位结果将在界面上创建具有高氢键和粘附力的冰状水层，从而导致非线性高摩擦。但是，施加负电位会导致金表面上有游离水，并且界面处的附着力可忽略不计，导致线性超低摩擦（摩擦系数约为0.004，处于超润滑状态）。定量描述了外部载荷和界面粘附如何影响摩擦力，这与实验结果非常吻合。因此，这项工作定量地揭示了超润滑状态和高摩擦状态之间电势控制切换的机理。通过电势控制界面行为可以激发纳米/微机电和纳米/微流体系统的新颖设计策略。这项工作定量地揭示了超润滑状态和高摩擦状态之间电势控制切换的机制。通过电势控制界面行为可以激发纳米/微机电和纳米/微流体系统的新颖设计策略。这项工作定量地揭示了超润滑状态和高摩擦状态之间电势控制切换的机制。通过电势控制界面行为可以激发纳米/微机电和纳米/微流体系统的新颖设计策略。