Elucidating the Effect of the Catalyst Layer Morphology on the Growth and Detachment of Bubbles in Water Electrolysis via Lattice Boltzmann Modeling.

The performance of water electrolysis is profoundly influenced by the behavior of the gas bubbles generated at the electrode surface. In order to improve the efficiency of bubble transportation, various nanostructures for the catalyst layer (CL), such as nanorods (NRs) or nanoparticles (NPs), have been proposed. However, there is still a lack of complete understanding about the relationship between the catalyst layer morphology and bubble evolution, which has a considerable impact on bubble transport. This study examines the effect of the catalyst layer morphology on the growth and detachment of bubbles in water electrolysis by employing the Lattice Boltzmann (LB) model. The performance of three different catalyst layer morphologies, namely, nanorods, nanoparticles, and hierarchical nanostructures, on bubble dynamics is estimated. The results suggest that the catalyst layer morphology is characterized by two factors: the bubble contact area and the electrochemically active surface area, which varies the bubble diameter, detachment time, and, subsequently, the bubble coverage. As a result, the energy efficiency of water electrolysis is influenced, aligned with experimental data that show a voltage differential of 148 mV at a current density of 0.65 A/cm ² . This study highlights the significance of improving the structure of the catalyst layer to boost the efficiency of water electrolysis systems.