Simultaneously Broadened Visible Light Absorption and Boosted Intersystem Crossing in Platinum-Doped Graphite Carbon Nitride for Enhanced Photosensitization

Herein, taking graphite carbon nitride ( g-C3N4) as the example, we demonstrated that the two limiting factors that determine the photosensitization performance, namely, light absorption and intersystem crossing (ISC), could be simultaneously enhanced through Pt2+ doping. Specifically, as a π-conjugated two-dimensional semiconductor, g-C3N4 is capable of absorbing light shorter than 460 nm (2.7 eV). Upon Pt2+ doping that allows metal-to-ligand charge transfer (MLCT) from Pt2+ to the substrate g-C3N4, the light absorption of g-C3N4 was greatly expanded up to 1000 nm. Meanwhile, the large atomic number of Pt2+ ensures promotion of ISC to activate the triplet state of g-C3N4 via heavy atom effect (HAE), which was confirmed via both photosensitization performance and photophysical characterizations. Further, the enhanced light absorption and photosensitization of Pt2+-doped g-C3N4 were harvested for antibiotics removal, a type of environment contaminants that gained global attention because of their worldwide abuse. Compared with its undoped counterpart, Pt2+-doped g-C3N4 featured significantly improved antibiotics removal in the presence of low-power white LED irradiation, which is promising for photosensitized environmental remediation.