Surface-Engineered 3D-Printed Polymeric Flat-Panel Photoreactors with P25 TiO₂ Nanoparticles for Photocatalytic...

In this work, a flat-panel photoreactor containing a serpentine channel was fabricated by LCD-based masked stereolithography and functionalized with commercial P25 TiO₂. Computational fluid dynamics (CFD) confirmed laminar flow over 2-10 mL min^-1 and described the velocity and wall-shear-stress distributions within the channel. Operating conditions were first established using suspended P25. Immobilization was then studied by varying binder type and content, P25 concentration and deposition method, together with pre-cure integration and direct printing of P25-loaded resin. The airbrushed P25/PARALOID™ B-72 coating provided the most favorable balance between reactor-level productivity and sustained response, with a post-maximum productivity retention of 47.8%. Direct printing reached the highest maximum apparent volumetric productivity (821.5 µmol H₂,eq L_reactor^-1 h^-1), corresponding to 1.7 and 2.1 times the values obtained with suspended and airbrushed configurations, respectively, but showed a much lower productivity retention of 12.9%. Post-mortem X-ray diffraction (XRD) and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) showed differences in P25 distribution and surface exposure among the tested configurations. These results show that the P25 incorporation strategy strongly affects both reactor-level productivity and operational stability.