To Configure Thin Layer Sonoelectrochemical Experiments

Abstract

In a thin layer sonoelectrochemistry cell, a simple high frequency (ultrasonic) oscillator placed a short distance from a flat electrode surface focuses ultrasound at the electrode solution interface to impact rates of interfacial processes. Traditionally, sonoelectrochemistry in a bulk fluid uses high energy oscillators such as sonic horns that drive turbulent cavitation. In the thin layer arrangement, no cavitation is visible but rates of interfacial electrochemical events are enhanced. Effective thin layer sonoelectrochemistry requires attention to properties of the solvent and electrode material, frequency and amplitude of the oscillator, and the alignment and distance between the faces of the oscillator and the electrode. When properly configured, the thin layer sonocell enhances energy delivered to the fluid electrode interface through constructive interference. Because there is no cavitation, voltammetric morphologies remain similar to those in quiescent electrolytes. Here, conditions to set up an effective thin layer sonoelectrochemical cell are described.

Why Sonochemistry in a Thin Layer? Constructive Interference

“…Dependent on parameters that include L, λ, ω, k, and reflectivity, construction of the thin layer cell is somewhat delicate. 24 Despite the limitations of the model assumptions, the outcomes of the model in underdamped conditions are consistent with the experimental results for sonoelectrochemistry undertaken in a thin layer configuration absent cavitation. 26,27 Solution.…”

“…It is noted that construction of TLS systems is more delicate than construction of CS systems. 24 Distinctions in TLS and CS. Resonance can be established in a thin fluid layer but not in a semi-infinite homogeneous fluid.…”

“…From voltammetry in an aqueous electrolyte, oxide layers on platinum electrodes are removed on extended sonication. Notably, during these experiments, where resonance is established, no cavitation is observed, perhaps because constructive interference focuses directional order across the fluid so that the localized, chaotic void collapses found in bulk fluids are avoided. The temperature of the fluid does not increase to within ≤1 °C, consistent with efficient energy transduction.…”

“…30 The sensitivity in construction of a thin layer sonoelectrochemical experiment that eliminates cavitation is noted. 24 Here, a one-dimensional model of sound pressure u(x, t) is derived for sonochemistry in a thin layer. From the solutions to a wave equation, advantages of TLS over CS are identified.…”

“…In common solvents, k ≲ 0.01 rad s −1 for T of the order of 10 6 . 24 Each oscillation builds energy at the interface. Kinetic rates of interfacial reactions are increased by energy deposited at the interface by high frequency sound pressure oscillations.…”