We report a method to dynamically control the surface of gallium-based liquid metal to switch between reflective/diffusive states by removing/depositing oxide films via electrochemical redox reactions. Electrochemical oxidation deposits rough surface oxides that are optically diffusive. Electrochemical reduction returns the metal to a pristine, smooth, and reflective state. This switching is achieved using only ±1.4V. In addition, a meniscus of liquid metal can be pumped to switch between concave/convex shapes. This work expands the range of optical applications of dynamic liquid metal surfaces.
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