Modelling can efficiently support the choice of the most interesting conceptual design approaches, material choices, and operating conditions for photoelectrochemical and photocatalytic devices. Here, I will discuss modeling of three different ideas for versatile and cheap solar hydrogen and syngas production: i) photocatalytic particle suspended in a solution, ii) semiconductor particle-based photoelectrodes (PEs) fabricated by scalable dipping procedures, and iii) high-temperature approaches to photoelectrochemistry.

Modeling of scalable photocatalysis suspensions require understanding of the single particle band energetics and kinetics and coupling it to the heat, mass and charge transport processes in a complete suspension. I will show how we use and couple 1D single particle models and 2D suspension simulations to provide material and design guidance of photocatalytic suspension approaches. Modeling of complicated particle-based PEs, on the other hand, requires full 3D multi-scale device models accounting for the morphological details of the nano-scale and then coupling them through homogenization theory to the macroscopic device model. I will show how we utilized nano-tomography to obtain the exact nano-scale morphology and how this morphology is incorporated into direct pore-level modeling to predict inhomogeneity in the variable fields and corresponding underutilization of parts of the PE. Finally, I will show how we use advanced 2D heat transfer models and detailed 1D junction models for mixed electron and ion conductor interfaces to model and explore high temperature approaches to photoelectrochemistry. I will end with a general outlook on modeling of photo-driven devices.