Photoelectrochemical (PEC) Flow Cell with Tandem Photoelectrodes (Two-Electrodes Configuration), CPECFCTP2E

A photoelectrochemical (PEC) flow cell represents the ultimate convergence of photovoltaics and continuous-flow electrochemistry, which integrates the light-absorbing semiconductor directly into the flow stack as the active electrode. To achieve continuous solar fuel generation, the cell must be built as a modified filter-press flow cell with severe optical requirements. (1) The Optical Window: The cell housing facing the sun must be a highly transparent, mechanically robust material, typically quartz or specialized borosilicate glass, capable of withstanding the internal pressure of the flowing liquid/gas reactants. (2) Transparent Current Collectors: Standard solid graphite or titanium bipolar plates would block the light. PEC cells use transparent conductive oxides (TCOs) like Fluorine-doped Tin Oxide (FTO) coated on glass, or finely woven titanium meshes that allow photons to pass through to the catalyst while still drawing the current away. (3) Flow Fields: The flow channels must be heavily modified. If the liquid electrolyte layer over the photoelectrode is too thick, the water will absorb specific wavelengths of light before they reach the semiconductor. The flow field must maintain a very thin, uniform liquid film across the active area.

References:

1. B. Liu, et al., Tandem cells for unbiased photoelectrochemical water splitting, Chem. Soc. Rev., 2023,52, 4644-4671.
2. M. S. Prévot, et al., Photoelectrochemical Tandem Cells for Solar Water Splitting, J. Phys. Chem. C 2013, 117, 35, 17879–17893.
3. J. H. Kim, et al., Overall Photoelectrochemical Water Splitting using Tandem Cell under Simulated Sunlight, ChemSusChem, 2016, 9, 61-66.