Ultrasound-enhanced alkaline water splitting with fast bubble release and sustained Ni catalysts

Abstract

Electrocatalytic water splitting is a promising approach to generate green hydrogen. However, mass production requires overcoming limitations associated with low efficiency as a result of gas bubble adhesion on the catalyst surface. Herein, we explored the significant impact of ultrasound as an external source to boost the electrolysis of nickel catalysts. It has been demonstrated that ultrasound accelerates bubble release (bubble resident time reduced up to 80 %) and improves electrocatalytic performance from 24 % to 43 %. Specifically, the physical and chemical effects generated by cavitation bubble collapse contribute to the overall production rate of H 2 by regenerating the catalyst’s active surface, reducing the overpotential, and facilitating the mass transfer. This study reveals a comprehensive understanding of the impact of ultrasound on the electrocatalytic activity for efficient H 2 production, opening an appealing opportunity for its implementation in the alkaline water-splitting process. • The physical effects of ultrasound waves promote fast release of O 2 /H 2 bubbles from electrode. • Ultrasonic irradiation reconstructs and reactivates catalyst surface to amorphous NiOOH layers. • Pulsed ultrasound reduces overpotential and accelerates charge transfer/mass transport. • Physicochemical effects of ultrasonic cavitation contribute to the overall production rate of H 2 .