Multibubble Detachment Characteristics of Regularly Distributed Nucleation Sites during Water Splitting

Abstract

Bubble detachment from electrode surfaces is crucial for enhancing the overall efficiency of water electrolysis. Arrayed microelectrodes have attracted considerable attention because of their superior gas evolution performance. However, without a clear understanding of bubble detachment behavior, existing electrode architecture optimizations are forced to proceed via empirical approaches. In this work, the detachment characteristics of multiple bubbles nucleated at regularly distributed on a photoelectrochemical water splitting electrode surface were systematically investigated by varying the nucleation site spacing and anodic current. By combining high speed imaging, electrochemical measurements, and particle image velocimetry, the critical role of bubble–bubble interactions during the detachment process was revealed. The results demonstrate that, in addition to buoyancy, both coalescence and hydrodynamic interactions generated by adjacent or the previous bubble can promote bubble detachment. As the dimensionless ratio of single bubble detachment radius to site spacing increases, bubble evolution progressively shifts from relatively independent behavior to stronger hydrodynamic interactions and ultimately to coalescence-dominated detachment. These interactions markedly alter the bubble detachment radius and the associated transport behavior. These findings elucidate the fundamental relationship between nucleation site spacing and gas evolution performance, providing guiding principles for the rational design and optimization of array microstructured electrodes.