Defect-rich ultrathin poly-heptazine-imide-framework nanosheets with alkali-ion doping for photocatalytic solar hydrogen and selective benzylamine oxidation
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Bo Liu1(
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Polymeric carbon nitride (CN) as a metal-free photocatalyst holds great promise to produce high-value chemicals and H2 fuel utilizing clean solar energy. However, the wider deployment of pristine CN is critically hampered by the poor charge carrier transport and high recombination. Herein, we develop a facile salt template-assisted interfacial polymerization strategy that in-situ introduces alkali ions (Na+, K+) and nitrogen defects in CN (denoted as v-CN-KNa) to simultaneously promote charge separation and transportation and steer photoexcited holes and electrons to their oxidation and reduction sites. The photocatalyst exhibits an impressive photocatalytic H2 evolution rate of 8641.5 μmol·g−1·h−1 (33-fold higher than pristine CN) and also works readily in real seawater (10752.0 μmol·g−1·h−1) with a high apparent quantum efficiency up to 18.5% at 420 nm. In addition, we further demonstrate that the v-CN-KNa can simultaneously produce H2 and N-benzylidenebenzylamine without using any other sacrificial reagent. In situ characterizations and DFT calculations reveal that the alkali ions notably promote charge transport, while the nitrogen defects generate abundant edge active sites, which further contribute to efficient electron excitation to trigger photoredox reactions.
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Defect-rich ultrathin poly-heptazine-imide-framework nanosheets with alkali-ion doping for photocatalytic solar hydrogen and selective benzylamine oxidation
), Bo Liu1(
)
Abstract
Polymeric carbon nitride (CN) as a metal-free photocatalyst holds great promise to produce high-value chemicals and H2 fuel utilizing clean solar energy. However, the wider deployment of pristine CN is critically hampered by the poor charge carrier transport and high recombination. Herein, we develop a facile salt template-assisted interfacial polymerization strategy that in-situ introduces alkali ions (Na+, K+) and nitrogen defects in CN (denoted as v-CN-KNa) to simultaneously promote charge separation and transportation and steer photoexcited holes and electrons to their oxidation and reduction sites. The photocatalyst exhibits an impressive photocatalytic H2 evolution rate of 8641.5 μmol·g−1·h−1 (33-fold higher than pristine CN) and also works readily in real seawater (10752.0 μmol·g−1·h−1) with a high apparent quantum efficiency up to 18.5% at 420 nm. In addition, we further demonstrate that the v-CN-KNa can simultaneously produce H2 and N-benzylidenebenzylamine without using any other sacrificial reagent. In situ characterizations and DFT calculations reveal that the alkali ions notably promote charge transport, while the nitrogen defects generate abundant edge active sites, which further contribute to efficient electron excitation to trigger photoredox reactions.
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Acknowledgements
This work was supported by the National Key Research and Development Program of the MOST (Nos. 2021YFA1500400 and 2018YFA0208603), the National Natural Science Foundation of China (NSFC, Nos. 21571167, 51502282, 22075266, and 21890751), and the Fundamental Research Funds for the Central Universities (Nos.WK2060190053 and WK2060190100). We acknowledge support from Hefei Science Center of Chinese Academy of Sciences, Fujian Institute of Innovation of Chinese Academy of Sciences. Y. W. thanks the Alexander von Humboldt Foundation for a postdoctoral fellowship.
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