Porous graphitic carbon nitride with nitrogen defects and cobalt-nitrogen (Co-N) bonds for efficient broad spectrum (visible and near-infrared) photocatalytic H2 production

The porous graphitic carbon nitride (g-C3N4) with nitrogen defects and cobalt-nitrogen (Co-N) bonds (g-C3N4-Co-K) is prepared by controllable copolymerization of melamine with KOH and Co(NO3)(2)center dot 6H(2)O. The method not only provides g-C3N4 with porous structure and Co-N bonds that accelerate photoexcited carrier transfer and endow numerous active sites, but also redshifts the g-C3N4 absorption edge into near-infrared (NIR) light region through the introduction of nitrogen defects and thus is suitable for H-2 evolution. The g-C3N4-Co-K exhibits significantly superior photocatalytic hydrogen generation performance (808 mu mol h(-1) g(-1)) under simulated solar light irradiation, about 15.5 times higher than pure g-C3N4, about 5.2 times higher than g-C3N4 with Co-N bonds (g-C3N4-Co), and about 2.1 times higher than g-C3N4 with nitrogen defects (g-C3N4-K). Interestingly, it is for the first time revealed that the synergistic effect of nitrogen defects and Co-N bonds result in enhanced H-2 generation activity (470 mu mol h(-1) g(-1)) under NIR light irradiation. (C) 2019 Elsevier Inc. All rights reserved.