Study of bubble evolution behavior on electrode surface based on lattice Boltzmann method

Abstract

Photoelectrochemical water splitting is regarded as one of the most efficient methods for hydrogen production, with photoelectrode materials playing a crucial role in enhancing its efficiency. To further improve the effectiveness of hydrogen production via photoelectrochemical water splitting, a lattice Boltzmann method (LBM) with multiple relaxation times (MRT) is employed to simulate the evolution of bubble growth, coalescence, and detachment on the photoelectrode surface. This simulation takes into account factors such as bubble detachment diameter, contact angle of the photoelectrode surface, and the spatial distribution of nucleation sites. According to simulation results, when the gravity coefficient increases, the bubble detachment diameter decreases, a contact angle between 120° and 140° is found to be optimal for bubble detachment. When the contact angle is less than 90°, the bubbles typically adhere to the surface of nucleation sites. The bubble detachment time decreases gradually as the contact angle ranges from 120° to 160°, and the bubble detachment time drops by 1.8 ms and 0.2 ms, respectively. When the distance between two nucleation sites was 5 μm, 10 μm, 15 μm, and 20 μm, and the bubble detachment time was 3 ms, 2.2 ms, 3 ms, and 2.9 ms, respectively. The bubble detachment time could be effectively reduced by appropriately increasing the distance between nucleation sites in a certain range. This study elucidates the behavior of bubbles on photoelectrode surfaces during photocatalytic water decomposition, providing valuable insights for optimizing photoelectrode design and improving the efficiency of hydrogen production.