Two birds with one stone: engineering polymeric carbon nitride with n-π∗ electronic transition for extending light absorption and reducing charge recombination
The weak visible light harvesting and high charge recombination are two main problems that lead to a low photocatalytic H2 generation of polymeric carbon nitride (p-CN). To date, the approaches that are extensively invoked to address this problem mainly rely on heteroatom-doping and heterostructures...
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Main Authors: | , , , , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
2023
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Subjects: | |
Online Access: | https://hdl.handle.net/10356/169204 |
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Institution: | Nanyang Technological University |
Language: | English |
Summary: | The weak visible light harvesting and high charge recombination are two main problems that lead to a low photocatalytic H2 generation of polymeric carbon nitride (p-CN). To date, the approaches that are extensively invoked to address this problem mainly rely on heteroatom-doping and heterostructures, and it remains a grand challenge in regulating dopant-free p-CN for increasing H2 generation. Here, we report utilizing the inherent n-π∗ electronic transition to simultaneously realize extended light absorption and reduced charge recombination on p-CN nanosheets. Such n-π∗ electronic transition yields a new absorption peak of 490 nm, which extends the light absorption edge of p-CN to approximately 590 nm. Meanwhile, as revealed by the photoluminescence (PL) spectra of p-CN at the single-particle level, the n-π∗ electronic transition gives rise to an almost quenched PL signal at room temperature, unravelling a dramatically reduced charge recombination. As a consequence, a remarkably improved photocatalytic performance is realized under visible light irradiation, with a H2 generation rate of 5553 μmol g−1∙h−1, ∼ 12 times higher than that of pristine p-CN (460 μmol∙g−1∙h−1) in the absence of the n-π∗ transition. This work illustrates the highlights of using the inherent n-π∗ electronic transition to improve the photocatalytic performance of dopant-free carbon nitrides. |
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