A Photocatalytic Panel Reactor is a large-area, low-profile system designed to scale up solar-to-fuel technologies from laboratory-scale powder suspensions to modular, industrial-ready panels. These reactors are primarily used for Solar Water Splitting (producing H2) and CO2 Reduction (producing CH4, CO, or formic acid) using direct sunlight as the sole energy source. Unlike concentrated solar reactors, panel reactors are designed to operate under "one-sun" (non-concentrated) conditions, making them more cost-effective for deployment over large land areas.

The goal of a panel reactor is to maximize the surface area exposed to sunlight while minimizing the depth of the water or gas layer to reduce mass transfer resistance. (1) Transparent Cover: High-transmittance, low-iron tempered glass or fluoropolymer (ETFE) sheets are used. These must be UV-stable and resistant to fouling. (2) Photocatalyst Layer: Instead of loose powder, the catalyst is typically immobilized on a substrate (like a glass plate, stainless steel mesh, or ceramic tile) to prevent the need for downstream filtration. (3) Thin-Layer Flow: The reactor maintains a liquid or gas layer only a few millimeters thick. This "thin-film" design ensures that light reaches the catalyst without being absorbed or scattered by a deep water column. (4) Manifold System: A header-and-branch piping system ensures that reactants are distributed evenly across the entire width of the panel, preventing "dead zones" where the catalyst might be underutilized.

References:

H. Nishiyama, et. al. Photocatalytic solar hydrogen production from water on a 100-m2 scale, Nature, 2021, 598, 304–307

V. Andrei, et. al. Solar Panel Technologies for Light-to-Chemical Conversion. Acc. Chem. Res. 2022, 55, 23, 3376–3386