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The employment of spin polarization under an external magnetic field holds great potential for the improvements of photocatalytic performance. However, owing to the huge difference in dielectric properties between ferromagnetic oxide and polymers, the photogenerated excitons with spin states are often limited to the ferromagnetic oxide wells, which leads to unsatisfactory activity. In this paper, a single-atom Co-doped C3N4 photocatalyst is successfully synthesized for photocatalytic water splitting and simultaneous oxidation of benzylamine. Under a tiny external magnetic field (24.5 mT), the hydrogen production rate could reach at 3979.0 μmol·g−1·h−1, which is about 340 times that of C3N4. Experimental results and theoretical calculations indicate that the interaction of Co d and N p orbital changes the symmetry center of C3N4, resulting in an increase in dielectric constant and spin polarization. Moreover, magnetic fields further promote parallel electron spin, and the increased number of charges with the parallel spin-down state is likely to dissociate under the action of an external magnetic field. On the other hand, the Co–N bond provides a huge built-in electric field and active site for strengthening the charge transfer and surface reaction. This work not only deepens the understanding of spin polarization, but also enriches methods to accelerate electron–hole separation.


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Insights into spin polarization regulated exciton dissociation and charge separation of C3N4 for efficient hydrogen evolution and simultaneous benzylamine oxidation

Show Author's information Gen Li1,§Xiaomei Sun1,§Peng Chen1( )Meiyang Song1Tianxiang Zhao1Fei Liu1( )Shuang-Feng Yin2( )
Provincial Guizhou Key Laboratory of Green Chemical and Clean Energy Technology, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
College of Chemistry and Chemical Engineering, Advanced Catalytic Engineering Research Center of the Ministry of Education, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, China

§ Gen Li and Xiaomei Sun contributed equally to this work.

Abstract

The employment of spin polarization under an external magnetic field holds great potential for the improvements of photocatalytic performance. However, owing to the huge difference in dielectric properties between ferromagnetic oxide and polymers, the photogenerated excitons with spin states are often limited to the ferromagnetic oxide wells, which leads to unsatisfactory activity. In this paper, a single-atom Co-doped C3N4 photocatalyst is successfully synthesized for photocatalytic water splitting and simultaneous oxidation of benzylamine. Under a tiny external magnetic field (24.5 mT), the hydrogen production rate could reach at 3979.0 μmol·g−1·h−1, which is about 340 times that of C3N4. Experimental results and theoretical calculations indicate that the interaction of Co d and N p orbital changes the symmetry center of C3N4, resulting in an increase in dielectric constant and spin polarization. Moreover, magnetic fields further promote parallel electron spin, and the increased number of charges with the parallel spin-down state is likely to dissociate under the action of an external magnetic field. On the other hand, the Co–N bond provides a huge built-in electric field and active site for strengthening the charge transfer and surface reaction. This work not only deepens the understanding of spin polarization, but also enriches methods to accelerate electron–hole separation.

Keywords: photocatalytic hydrogen evolution, C3N4, spin polarization, low magnetic field, benzylamine oxidation

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Publication history
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Acknowledgements

Publication history

Received: 28 December 2022
Revised: 08 February 2023
Accepted: 13 February 2023
Published: 13 April 2023
Issue date: July 2023

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© Tsinghua University Press 2023

Acknowledgements

Acknowledgements

This project was financially supported by the Guizhou Provincial Science and Technology Foundation (No. ZK2021069), the National Natural Science Foundation of China (No. 22268015), the Young Science and Technology Talents Development Project of Education Department in Guizhou Province (No. KY2022144), and the Innovation Group Project of Education Department in Guizhou Province (NO. 2021010). The authors would like to thank Shiyanjia Lab (www.shiyanjia.com) for materials characterizations.

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