Modeling/Simulation and Prototyping Development of Solar-Hydrogen Generators

A solar-driven water-splitting cell is generally comprised of light absorbers, electrocatalyts, membrane separators and an electrolyte solution in a specific system geometry.  The overall solar-to-hydrogen conversion efficiency of such a system depends on the performance and materials properties of all the individual components as well as the design of the system.  Significant advancements in modeling/simulation and prototyping development of solar-hydrogen devices have been made at Joint Center for Artificial Photosynthesis (JCAP).  In this talk, I will present a comprehensive multi-physics model for a solar-hydrogen cell that accounts for the performance of photoabsorbers and electrocatalyts and the transport properties of electrolytes and membrane separators.  The whole cell model was employed to optimize geometries of prototype designs, to define operational conditions and constraints for various system designs, to provide target materials properties and to evaluate the viability of new design concepts.  Specifically, the optimal band-gap combination of a tandem photoabsorbers, the performance limits in near-neutral pH electrolytes and the target transport properties of the membrane separators will be discussed in detail.  A few novel cell designs, including a vapor feed device and a solar concentrator coupled solar-hydrogen cell will also be discussed.  In the past years, guided by the modeling and simulation activity, a robust prototype, the louvered design, has been developed.  A solar-to-hydrogen conversion efficiency that exceeds 10% has been achieved in an integrated device with product gas separations.