Self-driven mercury motor via redox reaction in acid solution

Abstract

Recently, the deformation of liquid metals and self-driven liquid metal motors have received extensive close attention because of their wide applications. The construction of self-driven motors is based on the conversion of chemical energy into mechanical energy. Here, the reversible deformation of a mercury drop in NaIO₄ solution was investigated. The self-driven motion of a mercury drop in NaIO₄/H₂SO₄ solution was demonstrated for the first time. The mercury drop was oxidized in NaIO₄ solution, and then contacted with a metal foil swimming in an acid environment. The average speed of the mercury motor is 10 cm s⁻¹, which is faster than previously reported. The effects of the pH and the concentration on the movement were investigated. Besides, some interesting phenomena, such as pushing, colliding and bouncing between the mercury motor and the mercury drop, were investigated. We present the mechanism of self-driven motion and interaction between two mercury drops. The results demonstrate that the phenomenon should be attributed to the charge transfer, which caused the pressure difference on two ends of the mercury drop. These results have important significance for pressure sensing, mass transfer and the development of intelligent robots.