Boosting photocatalytic hydrogen production by creating isotype heterojunctions and single-atom active sites in highly-crystallized carbon nitride

Carbon nitride-based photocatalysts hold an enormous potential in producing hydrogen. A strategy to simultaneously create isotype heterojunctions and active sites in highly-crystallized carbon nitride is anticipated to significantly boost the photocatalytic activity, but is yet to be realized. Herein, we find that cobalt salt added in the ionothermal synthesis can promote the phase transition of heptazine-based crystalline carbon nitride (CCN) to triazine-based poly(triazine imide) (PTI), rendering the creation of single-atom cobalt coordinated isotype CCN/PTI heterojunction. Co-CCN/PTI exhibits an appreciable apparent quantum yield of 20.88% at 425 nm for photocatalytic hydrogen production with a rate achieving 3538 mu mol h(-1) g(-1) (lambda > 420 nm), which is 4.8 times that of CCN and 27.6 times that of PTI. The high photocatalytic activity is attributed to the Type II isotype highly-crystallized CCN/PTI heterojunction for promoting charge carrier migration, and the single-atom Co sites for accelerating surface oxidation reaction. (c) 2021 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Automated summary

The addition of cobalt salt promotes the phase transition of carbon nitride and creates single-atom cobalt coordinated heterojunctions, leading to enhanced photocatalytic activity for hydrogen production.