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    Band structure engineering and efficient injection rich-pi-electrons into ultrathin g-C3N4 for boosting photocatalytic H-2-production

    Year: 2020

    Journal: Appl. Surf. Sci., Volume 505, MAR 1

    Authors: Che, Huinan; Li, Chunxue; Zhou, Pengjie; Liu, Chunbo; Dong, Hongjun; Li, Chunmei

    Organizations: National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [21805115, 21576112, 21606114]; NSFC-Shanxi Coal Based Low Carbon Joint Fund [U1810117]; Postdoctoral Science Foundation of ChinaChina Postdoctoral Science Foundation [2017M611712, 2017M611717]; Jiangsu Planned Projects for postdoctoral Research Funds [1701025A]; Scientific Research Foundation for Senior Talent of Jiangsu University [17JDG020]

    Keywords: g-C3N4; Rich-pi-electrons; Photocatalytic H-2 evolution, -CH defects; H-2 adsorption energy

    Simultaneously regulate energy band structure and efficient injection rich-pi-electrons to achieving high photocatalytic H-2 evolution (PHE) activity are highly desirable. Herein, the C-substitution for N to the formation of C=C in ultrathin g-C3N4 was prepared by urea and pi-electron-rich 2-Aminopyrimidine copolymerization. DFT theory calculations and experimental results exhibit that introduction of C=C into ultrathin g-C3N4 not only narrows its band gap from 2.7 eV to 2.48 eV and produce a large number of -CH defects, but also effectively boosts the dissociation of photogenerated excitons and reduces hydrogen (H-2) adsorption energy. Additionally, compared to the pure g-C3N4, the introduction of C=C into ultrathin g-C3N4 also can increase visible light absorption and shift up the conduction band (CB) position for favor of proton reduction to produce H-2. As a result, the PHE activity of optimal C-substitution for N to obtained g-C3N4 (1840.38 mu mol h(-1) g(-1)) is higher than 6.06 times that of pure g-C3N4 under the visible-light irradiation. And the AQE value is evaluated to be 4.8% at 420 nm. This work provides a promising strategy for developing high-efficiency photocatalyst through band structure engineering and efficient injection rich-pi-electrons.
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