Self‐Supporting 3D Boron‐Based Photocatalyst Prototype for Water Treatment

The development of robust and efficient photocatalysts (PhCs) is crucial for enhancing solar water treatment, which is currently limited by conventional catalyst formats such as particle suspensions, membranes, and fiber mats. These formats often suffer from catalyst leakage, poor light penetration, and low mechanical stability. This study addresses these challenges by developing self‐supporting 3D PhCs. A homogeneous photoresin based on boron methacrylate was synthesized and used for stereolithographic 3D printing to fabricate polymer architectures. These structures were subject to controlled pyrolysis under vacuum and nitrogen atmospheres at temperatures up to 1800C. Chemical and structural transformations were characterized using H nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermal analysis, X‐ray diffraction, and scanning electron microscopy. Photocatalytic activity was evaluated by monitoring Rhodamine B decolorization under halogen lamp irradiation. The fabricated architectures retained their structural integrity and geometry during pyrolysis. Photocatalytic performance was strongly dependent on the annealing conditions. The highest photocatalytic performance was achieved when the phase consisted of amorphous carbon and crystalline boron nitride, exhibiting dye destruction efficiencies of up to 99.94%. These results demonstrate that stereolithographic fabrication of boron methacrylate structures followed by pyrolysis yields durable, reusable, and light‐accessible 3D PhCs. This approach addresses the limitations of conventional photocatalytic formats and offers new opportunities for efficient water treatment.