Electrodeposition of copper in the presence of an acoustically excited gas bubble

Abstract

Copper has been electrodeposited in the presence of an acoustically excited gas bubble (Ar bubbles with radii ~1.5 mm held below a copper plate). Under the conditions employed, an acoustic pressure amplitude of 69.5 Pa is sufficient to excite multiple surface wave modes on the bubble wall. This is observed using high-speed imaging. This oscillation generates significant micromixing, which brings fresh electrolyte to the electrode surface leading to an enhanced deposition current. Scanning electron microscopy (SEM) reveals radial streaming patterns in the resulting copper deposit. Experiments carried out using a lower acoustic pressure amplitude of 50.5 Pa (such that only the Faraday wave is excited) exhibit a lesser degree of streaming and mass transfer enhancement. No significant enhancement is seen if the bubble is undergoing breathing mode oscillation.

A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification

“…4 and Video S1, † the slug bubble's surface vibrated fiercely without collapsing, indicating that it undergoes non-inertial cavitation. 15,65,66 The bubble in our experiment was confined by the microchannel and had a slug shape, but the cavitation behavior still corresponded to the above fact. It includes various oscillation modes depending on the acoustic pressure.…”

Formation of dish-like holes and a channel structure in electrodeposition of copper under hydrogen co-deposition

“…These channels were generated in situ by the simultaneous processes of copper growth and vigorous hydrogen evolution. It is also known [19] that a channel or a stream copper structure can be formed ex situ by the use of an acoustically excited Ar gas bubble.…”

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