Geometry effect on titania nanoparticle distribution and its impact on the photocatalytic properties of vat photopolymerization 3D-printed acrylic resin-based nanocomposites

The development of geometrically optimized photocatalytic devices is a key challenge for advancing environmental purification technologies. The incorporation of titanium dioxide (TiO2) nanoparticles into polymeric materials, combined with additive manufacturing, offers a promising route to fabricate photocatalytic structures with custom-designed architectures. This paper investigates how specific geometric design influences nanoparticle distribution and its effect on the photocatalytic performance. A commercial acrylic resin was loaded with different TiO2 concentrations (2.5, 5, 10 wt%), and optimal printing conditions were identified to achieve high-resolution structures. Characterization through cure depth measurements, ATR-FTIR spectroscopy, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy confirmed effective photopolymerization and thermal stability, enabling evaluation of nanoparticle distribution in 3D-printed nanocomposites. Gyroid, lattice, and wheel geometries were designed to assess shape effects on titania distribution via photocatalytic testing. Topologically constrained and intralayer regions promote nanoparticle surface enrichment. Specifically, complex networks exhibit greater surface segregation than simple geometries, enhancing TiO2 photoactivity. The gyroid, characterized by the highest number of layers, displayed the best photocatalytic activity, with a 43% increase in the reaction rate constant compared to the wheel geometry at 10 wt% TiO2. These findings demonstrate that tailoring material formulation and geometry can maximize the performance of 3D-printed photocatalytic devices.