Abstract
In this study, a fully coupled three-dimensional multiphysics CFD model of a photoelectrochemical (PEC) water splitting cell incorporating a ZnO/BiVO4 photoanode was developed using COMSOL Multiphysics® 6.1. The model integrates semiconductor charge transport, ionic transport (diffusion, migration, and convection), electrochemical kinetics, and fluid dynamics within a widely adopted experimental configuration. This work focuses on coupling the dominant transport phenomena governing macro-scale PEC behavior under realistic operating conditions, allowing the overall PEC behavior to be captured without resolving microscopic interfacial complexities. The simulation results show good agreement with previously reported experimental data in terms of photocurrent density, demonstrating the capability of the model to reproduce photocurrent behavior. The developed framework provides insight into the interplay between photogenerated charge transport and electrochemical reactions and can serve as a predictive tool for analyzing and optimizing PEC system performance prior to experimental implementation.