Regulation of Bubble Behavior on a TiO₂ Photoelectrode Surface during Photoelectrocatalytic Water Splitting

Abstract

The mass transfer limitation of gas products in heterogeneous photocatalytic reactors is a key step in governing the reaction efficiency, and the bubble behavior on the catalyst surface directly affects the mass transfer process. In this study, a method for the directional regulation of bubble behavior by the periodic chopping was proposed. The specific chopping modes drove the bubble to bounce on the photoelectrode surface, and the growth curve of the bouncing bubble was stepped. The bubble bouncing characteristics were directionally regulated by adjusting the chopping mode, and the bubble growth time and detachment diameter were significantly reduced. A force analysis model of the bubble bouncing process was established, and a multiphysics simulation of the bubble bouncing behavior was performed. The competition of forces is the physical mechanism that drives the bubble to bounce, and the thermal Marangoni force is the driving force that causes the bubble to return. The heat and mass transfer processes were dominated by convection, and the bubble bouncing behavior could significantly enhance convective transport near the photoelectrode surface. This paper provides an experimental and theoretical basis for promoting the bubble detachment and the heat and mass transfer rate on the gas evolving electrode surface during photoelectrocatalytic conversion.