Distribution Characteristics of Multiphysics around the Bubble on the Surface of Photoelectrode

Abstract

In the heterogeneous photocatalytic reaction systems, the evolution of bubbles on the catalyst surface is a complex process that depends on multiple factors, such as the solid–liquid interface structure, solution properties of the reaction system, and multiphysics interactions, and directly affects energy and mass transport processes. This study investigated the multiphysics distribution around a bubble and the bubble detachment characteristics on the surface of a TiO2 photoelectrode during photoelectrocatalytic water splitting. The bubble diameter had an effect on the distribution of the light field in the system, affecting the temperature and flow distributions of the electrolyte around the bubble. Marangoni convection was induced by the inhomogeneous temperature distribution along the bubble interface, which enhanced the heat and mass transfer near the reaction site. It was also demonstrated that an increase in laser power increased Marangoni convection on the bubble surface, thus delaying bubble detachment. A force model for predicting the bubble detachment diameter that considered the coupling effect between the light, temperature, and flow fields was developed. The predicted bubble detachment diameters agreed well with the experimental results within an error of ±10%.