Designing 3D-Printed TiO ₂ /BiFeO ₃ -Hybrid Materials for Enhanced Photocatalytic Degradation of Acyclovir via Visible Light

3D-printed porous TiO 2 /BiFeO 3 nanocomposite monoliths with surface areas of up to 65 m 2 g –1 were fabricated via two ways employing 3D printing. In method A, BiFeO 3 nanoparticles were directly embedded into a TiO 2 -based hybrid ink for the direct ink writing (DIW) technique, while in method B, BiFeO 3 nanoparticles were deposited as a surface coating onto a 3D-printed TiO 2 scaffold. The obtained materials were comprehensively characterized by X-ray diffraction (XRD), electron microscopy (SEM, TEM), nitrogen adsorption–desorption, UV–vis spectroscopy, photoluminescence spectroscopy, and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance of the materials was evaluated for the degradation of acyclovir under three different irradiation conditions: a medium-pressure Hg lamp (emission mostly in the UV region, 150 W) and blue LED sources at 420 nm (6 W) and 440 nm (40 W). The sample prepared by method A, including 1 wt % BiFeO 3 inside a TiO 2 matrix, showed the best performance under all irradiation conditions, which could be attributed to the combination of high surface area and the improved charge separation across the heterojunction interface. Additionally, Density Functional Theory (DFT) calculations were performed to confirm the formation of type-II heterojunctions between BiFeO 3 embedded in TiO 2 materials, consistent with the experimentally observed enhancement. These 3D-printed materials represent a significant advancement toward the development of photocatalytic water treatment under visible light conditions.