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.

中文翻译：

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D–π–A型三苯胺染料共价官能化的g-C3N4用于高效光催化氢的释放

通过在gC ₃ N ₄纳米片（gC ₃ N ₄ NSs）之间生成酰胺共价键，首次制备了两种新型的共价键光催化剂gC ₃ N ₄ NSs / TC1和gC ₃ N ₄ NSs / TC2。和由三苯胺型染料，2-氰基-3-（4-（二苯氨基）苯基）丙烯酸（TC1）或3,3'-（4,4'-（苯基氮杂二基）双（4,1-）合成的酰氯亚苯基））双（2-氰基丙烯酸）（TC2）。实验结果表明，三苯胺D–π–A型有机染料部分成功地与gC ₃ N ₄共价键合，并且可以扩展gC ₃ N ₄ NSs / TC1和gC ₃ N ₄ NSs / TC2的光谱响应区域。约460 nm至600 nm以上 由于引入了酰胺共价键，所构建的gC ₃ N ₄ NSs / TC1光催化剂显示出显着增强的H ₂析出活性，约为73 555.8μmolh ^-1 g ^-1并在420 nm，500 nm，520 nm和600 nm单色光下分别表现出35.2％，27.1％，16.9％和5.4％的高表观量子产率。与纯gC ₃ N ₄ NSs的结果相比，在可见光照射下，具有酰胺共价键的gC ₃ N ₄ NSs / TC1的H ₂生产率提高了约100倍，AQY值提高了978倍。与gC ₃ N ₄ NSs / TC1相比，gC ₃ N ₄ NSs / TC2的H ₂释放活性略低，约为70 986.8μmolh ^-1g ^-1。结合实验和密度泛函理论（DFT）的计算结果，可以推测出一种可能的机制，即gC ₃ N ₄ NSs / TC1的电子和几何结构更有利于激发状态下的电荷分离和电子传输的单向性比gC ₃ N ₄ NSs / TC2高。研究表明，通过共价键将简单的三苯胺型染料引入gC ₃ N ₄的表面导致官能化部分与gC ₃ N ₄之间的强共价相互作用。协同改善电子和光学性能以及光催化性能。本工作强调了通过后修饰将有机染料共价官能化的gC ₃ N ₄用作新型光催化剂在H ₂生产中的潜在用途。