For the efficient photocatalytic activity of polymeric photocatalysts, it is necessary to construct effective charge-transfer channels as well as to promote charge mobility. Here, KCl/LiCl salt assisted polycondensation is proposed to synthesize polymeric carbon nitride with a controllable molecular structure. It is notable that the cross-linking degree and the building blocks can be controlled by the ratio of KCl/LiCl. Specifically, with an increasing KCl content in the KCl/LiCl salt system, the product gradually changes from a highly cross-linked two-dimensional carbon nitride to an almost non-crosslinked one. This decreasing cross-linking degree is accompanied by a continuous change of the molecular units from triazine to heptazine. The cross-linking can serve as the inter-chain charge-transfer channel whereas more conjugated subunits will improve the charge mobility. By optimizing the KCl content, effective inter-chain charge transfer and high charge mobility can be realized simultaneously. The optimized polymeric carbon nitride exhibits excellent photocatalytic performance for both H₂O₂ and H₂ production. Significantly, the apparent quantum efficiency (AQE) for H₂O₂ production reaches 56.6% at 420 nm, which is much higher than that of most of the reported carbon nitride-based photocatalysts.

中文翻译：

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聚合氮化碳中的有效链间电荷转移和高电荷迁移率源于可控分子结构，可增强光催化 H2O2 和 H2 的生产

为了实现聚合物光催化剂的高效光催化活性，有必要构建有效的电荷转移通道并促进电荷迁移率。在此，提出了KCl/LiCl盐辅助缩聚来合成具有可控分子结构的聚合氮化碳。值得注意的是，交联度和结构单元可以通过 KCl/LiCl 的比例来控制。具体而言，随着KCl/LiCl盐体系中KCl含量的增加，产物逐渐从高度交联的二维氮化碳转变为几乎非交联的碳氮化物。交联度的降低伴随着分子单元从三嗪到七嗪的连续变化。交联可以作为链间电荷转移通道，而更多的共轭亚基将提高电荷迁移率。通过优化KCl含量，可以同时实现有效的链间电荷转移和高电荷迁移率。优化的聚合氮化碳对于H ₂ O ₂和H ₂的生产均表现出优异的光催化性能。_{值得注意的是，在420 nm处，产生H 2} O _{2 的}表观量子效率（AQE）达到56.6%，远高于大多数已报道的氮化碳基光催化剂。