ｇ－Ｃ３Ｎ４／半導体複合材料の構築と表界面制御による二酸化炭素光還元の高機能化

该项目主要侧重于探索基于可见光响应有机半导体（即氮化碳）的高效光催化剂，用于化学燃料生产。我们一直致力于通过以下两种途径增强载流子的分离和输运，并取得了重大进展：1)构建了由低分子量氮化碳和Co卟啉组成的亚胺连接天线反应中心配合物；其中，由于电子容易被Co（II）捕获形成Co(I)物质，光生成的电子空穴分离效率更高，固定在C-N骨架上的活性位点有利于氧化还原光催化反应；2)通过控制七嗪前驱体的自组装和组装前驱体的煅烧，设计出平面内有序增强的氮化碳，从而大大增强光生载流子的平面内输运。结果表明，尽管煅烧过程中升温速率不同，组装后的七嗪前驱体在缩聚过程中仍能保持亚微棒状形态，无体积收缩。石墨平面内的有序增强和诱导的良好电荷分离使得H2在可见光（λ > 420 nm）下的析出速率大幅提高，达到420 umol/h，在420 nm处的表观量子效率达到8.9%，这是文献中c3n4相关光催化剂的最高效率之一。

The project is mainly focused on exploring highly efficient photocatalysts for chemical fuel production based on visible-light responsive organic semiconductor, i.e. carbon nitride. We have been devoted to enhance the charge carrier separation and transport through the following two pathways and have obtained significant progress:1) Constructing an imine-linked antenna-reaction center complex composed of low-molecular-weight carbon nitride and Co porphyrin, where the photo-generated electron-hole is separated more efficiently since electrons could be easily trapped by Co(II) to form Co(I) species and the active site immobilized on the C-N framework facilitated the redox photocatalytic reaction;2) Designing carbon nitride with enhanced in-planar ordering by controlling the self-assembly of heptazine precursors and calcination of the assembled precursors, where the intraplanar transport of the photo-generated charge carriers can be largely enhanced. It was found that the sub-micro rod-like morphology of the assembled heptazine precursor was well maintained during the poly-condensation without volumetric shrinkage in spite of different temperature-rise rates in the calcination process. The enhanced ordering within the graphitic planar and the induced excellent charge separation contributed to a tremendously improved H2 evolution rate of 420 umol/h under visible light (λ > 420 nm) with an apparent quantum efficiency of 8.9% at 420 nm, which is among the highest value for C3N4-related photocatalyst in the literature.