3D-Printed Organic Conjugated Trimer for Visible-Light-Driven Photocatalytic Applications

Small molecule organic semiconductors (SMOSs) have emerged as a new class of photocatalysts that exhibit visible light absorption, tunable bandgap, good dispersion, and solubility. However, the recovery and reusability of such SMOSs in consecutive photocatalytic reactions is challenging. This work concerns a 3D-printed hierarchical porous structure based on an organic conjugated trimer, named EBE. Upon manufacturing, the photophysical and chemical properties of the organic semiconductor are maintained. The 3D-printed EBE photocatalyst shows a longer lifetime (11.7 ns) compared to the powder-state EBE (1.4 ns). This result indicates a microenvironment effect of the solvent (acetone), a better dispersion of the catalyst in the sample, and reduced intermolecular π-π stacking, which results in improved separation of the photogenerated charge carriers. As a proof-of-concept, the photocatalytic activity of the 3D-printed EBE catalyst is evaluated for water treatment and hydrogen production under sun-like irradiation. The resulting degradation efficiencies and hydrogen generation rates are higher than those reported for the state-of-the-art 3D-printed photocatalytic structures based on inorganic semiconductors. The photocatalytic mechanism is further investigated, and the results suggest that hydroxyl radicals (HO⋅) are the main reactive radicals responsible for the degradation of organic pollutants. Moreover, the recyclability of the EBE-3D photocatalyst is demonstrated in up to 5 uses. Overall, these results indicate the great potential of this 3D-printed organic conjugated trimer for photocatalytic applications.