Naphthalimide-porphyrin hybridized graphitic carbon nitride for enhanced photocatalytic hydrogen production

A series of NP/g-C3N4 hybrids of graphitic carbon nitride (g-C3N4) with naphthalimide-porphyrin (NP) are developed for photocatalytic hydrogen production. Planar naphthalimide-porphyrins are facilely adsorbed onto flexible two-dimensional g-C3N4 through pi-pi stacking. Except for its function as photosensitizer, NP in the hybrid could efficient inhibit the charge recombination by electron transfer from the lowest unoccupied molecular orbital (LUMO) of NP to conduction band of g-C3N4, meanwhile facilitate Forster energy transfer from g-C3N4 donor to NP acceptor for the efficient overlap of absorption spectrum of NP and emission of g-C3N4. As a result, the hybrid 2%NP/g-C3N4 containing 2% weight ratio of NP exhibits an impressive photocatalytic hydrogen production rate (HPR) of 2297 mu mol g(-1) h(-1), while pristine g-C3N4 shows a HPR of 698 mu mol g(-1) h(-1). Specifically, the performance of 2%NP/g-C3N4 is far superior compared with the hybrids of g-C3N4 with Zn(II)-tetrakis(4-carboxylphenyl)porphyrin (ZnTCPP) and Zn(II)-tetrakis(4-phenyl)porphyrin (ZnTPP) in photocatalytic hydrogen production under the same conditions.