Porous defect-modified graphitic carbon nitride via a facile one-step approach with significantly enhanced photocatalytic hydrogen evolution under visible light irradiation
Porous defect-modified graphitic carbon nitride via a facile one-step approach with significantly enhanced photocatalytic hydrogen evolution under visible light irradiation
复制标题
通过一种简便的一步法制备多孔缺陷改性石墨氮化碳，在可见光照射下显着增强光催化析氢
DOI：
10.1016/j.apcatb.2017.12.044
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Zhongkui Zhao
中科院分区：
文献类型：
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作者：
Di Zhang;Yongle Guo;Zhongkui Zhao
石墨碳氮化物（g-C3 N4）被认为是最有前途的太阳能转化光催化剂之一。但其固有的可见光吸收不足和电荷分离效率差的缺点严重限制了其在可见光光催化制氢中的实际应用。本文提出了一种简单的一步合成方法，通过在氮气气氛下，将双氰胺（DCDA）和氯化铵（NH 4Cl）的混合物进行热聚合反应，在g-C3 N4骨架中同时引入两种缺陷（氰基和氮空位）和多孔结构，制备了一种新型的多孔缺陷改性石墨碳氮化物（P-DCN）.结果表明，合成的P-DCN在可见光照射下的析氢速率（HER）比本体g-C3 N4高26倍，达到20.9 μmol h−1。结合多孔和缺陷特性，P-DCN甚至分别比高活性多孔石墨氮化碳（P-CN）和缺陷改性的g-C3 N4（DCN）表现出高2.0和1.8倍的HER。其优异的光催化制氢性能源于其可见光捕获能力的显著提高、光生载流子的分离和复合抑制作用的显著促进以及多孔结构、缺陷和比表面积的综合作用所导致的活性中心数量的增加和传质的增强。此外，这种方法可以提供一个新的见解，设计高效的可见光光催化剂的其他转换，包括CO2还原，环境修复，和有机合成过程。
Graphitic carbon nitride (g-C3N4) has been considered as one of the most promising photocatalysts for solar energy conversion. However, the intrinsic drawbacks of insufficient visible-light absorption and poor charge separation efficiency seriously limit its practical applications in visible light photocatalytic hydrogen evolution. In this work, a facile one-step strategy was proposed to construct a novel porous defect-modified graphitic carbon nitride (P-DCN) via thermal polymerization of a freeze-dried crystalline mixture containing dicyandiamide (DCDA) and ammonium chloride (NH4Cl) under nitrogen atmosphere, in which both porous feature and two types of defects (cyano group and nitrogen vacancy) were simultaneously introduced into g-C3N4framework. Results show that the as-synthesized P-DCN Exhibits 26 times higher hydrogen evolution rate (HER) under visible light irradiation than bulk g-C3N4, reaching 20.9 μmol h−1. In combination of porous and defective characteristics, P-DCN even demonstrates 2.0 and 1.8 folds higher HER than highly active porous graphitic carbon nitride (P-CN) and defect-modified g-C3N4(DCN), respectively. The outstanding photocatalytic performance for hydrogen production originates from the remarkably improved visible light harvesting capability, the notably promoted separation and recombination inhibition of photoinduced charge carriers, and the increased amount of active sites and the strengthened mass transfer resulting from the combination effect of the porous feature, as-formed defects, and the enlarged specific surface area. Moreover, this approach could render a new insight for designing highly efficient visible light photocatalysts for the other transformations including CO2reduction, environmental remediation, and organic synthesis process.