Development and optimization of a device for testing photocatalysts in continuous flow regime

• CFD evaluated three photocatalytic reactor designs: DEVAW, DEVTR, and DEVTW. • DEVTW (5 mm height) proved optimal with minimal dispersion and ideal RTD. • Mass transfer simulations confirmed that DEVTW achieved the highest oxygen output. • DEVAW simulations reveal reaction limits, requiring further investigation of catalyst properties. This work combines computational fluid dynamics (CFD) simulations with experimental validation to optimize a photocatalytic reactor for oxygen (O 2 ) production. By addressing key chemical diffusion limitations in heterogeneous photocatalysis, the study aims to optimize reactor geometry and enhance its performance. CFD simulations were employed to assess the performance of three devices (DEVAW, DEVTR, and DEVTW) with different shapes and depths under similar operational conditions. Three-dimensional (3D) CFD simulations were conducted to analyze the hydrodynamic behavior and the Residence Time Distribution (RTD) at a flow rate of 10 cm 3 min -1 . Results demonstrate that the DEVTW reactor, at a height of 5 mm, achieved superior molar fluxes and a higher O 2 concentration of 158 µM, compared with the DEVAW and DEVTR reactors of the same height, which reached 140 µM and 144 µM, respectively. The superior O 2 concentration is attributed to the increased velocity gradient near the catalytic plate, which facilitates mass transfer by improving convective transport of O 2 from the catalyst surface and promotes the diffusion of O 2 molecules. Mass transfer CFD simulations further indicate that the chemical reaction is the rate-limiting step, revealing that the DEVTW device is adequate for efficient photocatalyst screening in dissolved O 2 evolution reactions.