Chladni figures reduce ohmic losses in alkaline electrolysis

An method for hydrogen bubble removal through ultrasonic excitation applied directly through the cathode is presented in this work. High-speed imaging, pressure field measurements, and overvoltage monitoring were employed to characterize how cathode vibration in the 100 kHz range influences electrolytic efficiency. Upon the start of the vibration, hydrogen bubbles detached and migrated across the surface, forming distinct spatial patterns corresponding to the electrode's vibrational modes and resembling Chladni figures. The bubble migration is dominated by the primary Bjerknes force arising from acoustic pressure gradients. This is confirmed by the Keller-Miksis model which predicts the observed movement of the bubbles to the pressure nodes. The work demonstrates that electrode vibrations significantly reduced ohmic losses, with overvoltage dropping 20% within 100 ms during a 2 s activation period. The voltage required 7 s to return to initial values after deactivation, indicating that pulsed vibration strategies can achieve superior efficiency compared to continuous running setups.