Issue 6, 2020

D–π–A-type triphenylamine dye covalent-functionalized g-C3N4 for highly efficient photocatalytic hydrogen evolution

Abstract

Two novel covalent bond photocatalysts, namely, g-C3N4NSs/TC1 and g-C3N4NSs/TC2 were prepared for the first time via the generation of an amide covalent bond between g-C3N4 nanosheets (g-C3N4NSs) and acyl chloride synthesized from triphenylamine-type dyes, 2-cyano-3-(4-(diphenylamino)phenyl)acrylic acid (TC1) or 3,3′-(4,4′-(phenylazanediyl)bis(4,1-phenylene))bis(2-cy-anoacrylic acid) (TC2). The experimental results indicated that triphenylamine D–π–A-type organic dye moieties covalently bonded to g-C3N4 successfully and the spectral response regions of both g-C3N4NSs/TC1 and g-C3N4NSs/TC2 could be extended from ∼460 nm to more than 600 nm. Due to the introduced amide covalent bond, the constructed g-C3N4NSs/TC1 photocatalyst showed remarkably enhanced H2 evolution activity with about 73 555.8 μmol h−1 g−1 and exhibited high apparent quantum yields (AQY) of 35.2%, 27.1%, 16.9% and 5.4% at 420 nm, 500 nm, 520 nm and 600 nm monochromatic light, respectively. Compared with the results for pure g-C3N4 NSs, about 100 times higher H2 production rate and 978 times higher AQY value were obtained for g-C3N4NSs/TC1 with the amide covalent bond under visible light irradiation. Compared to g-C3N4NSs/TC1, g-C3N4NSs/TC2 exhibited slightly lower H2 evolution activity with about 70 986.8 μmol h−1 g−1. Combining the experimental and density functional theory (DFT) calculation results, a possible mechanism can be conjectured that the electronic and geometric structures of g-C3N4NSs/TC1 are more conducive to the charge separation and the unidirectionality of electron transport in the excited state than those of g-C3N4NSs/TC2. The research reveals that this introduction of simple triphenylamine-type dyes into the surface of g-C3N4via covalent links results in a strong covalent interaction between functionalized moieties and g-C3N4 to synergistically improve the electronic and optical properties and photocatalytic performance. The present work highlights the potential use of organic dye covalent-functionalized g-C3N4via post modification as a novel photocatalyst in applications such as H2 production.

Graphical abstract: D–π–A-type triphenylamine dye covalent-functionalized g-C3N4 for highly efficient photocatalytic hydrogen evolution

Supplementary files

Article information

Article type
Paper
Submitted
04 Jan 2020
Accepted
21 Feb 2020
First published
21 Feb 2020

Catal. Sci. Technol., 2020,10, 1609-1618

D–π–A-type triphenylamine dye covalent-functionalized g-C3N4 for highly efficient photocatalytic hydrogen evolution

C. Zhang, J. Liu, X. Liu and S. Xu, Catal. Sci. Technol., 2020, 10, 1609 DOI: 10.1039/D0CY00013B

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