Enhancing the Photocatalytic Activity via Direct Covalent Functionalization in Single-Walled Carbon Nanotubes

Herein, the direct covalent functionalization of single-walled carbon nanotubes (SWNT) is presented with an amino-decorated phenyl-phenothiazine (PTH-NH2) organophotocatalyst through the diazonium chemistry protocol. Three different SWNT-PTH hybrids are prepared by varying the amount of PTH-NH2 and diazonium agent and are fully characterized. These hybrids differ not only in the degree of functionalization, but also in the chemical structure and the photophysical properties. The study shows that these features affect the photoredox activity of the materials in the photo-debromination of aromatic halides. Thus, sample SWNT-PTH-5, a functionalized nanotube with a 5% wt loading of PTH, surpasses the catalytic performance of homogeneous PTH in 11 different substrates, finishing the reaction in shorter times, in a recyclable manner and without catalyst leaching. This study demonstrates the importance of controlling the functionalization degree of SWNT with photocatalysts to prepare photocatalytic materials with even higher catalytic activity than that presented by the homogeneous PTH catalyst. The control on the direct functionalization of single-walled carbon nanotubes with the organophotocatalyst PTH allowed the creation of hybrid materials with enhanced charge transfer properties able to overcome homogeneous counterparts in the photoreductive debromination of aromatic halides with a robust character toward the stability during operation, including wide scope and synthetic utility.image