Photocatalytic technology provides a new strategy for mitigating energy crisis. The development of photocatalytic materials with high efficiency and stable visible light response has always been the direction of researchers in the field of photocatalysis. Graphite carbon nitride (g-CN) has attracted ever increasing attention in the field of photocatalysis due to its special characteristics (such as visible light response, high stability, and low cost). However, the low separation efficiency of photogenerated electrons and holes limits its catalytic activity. In this paper, a novel g-CN-based intramolecular donor–acceptor (D–A) system was prepared to promote the separation efficiency of light-induced charge carriers. The catalyst is prepared from g-CN and 1,2-dibromobenzene (Bz) through a simple calcination method. Characterization results confirmed that Bz was successfully introduced into the g-CN (g-CN-Bz (x)) framework. The formation of the D–A structure leads to the spatial separation of electrons and holes pairs, which significantly accelerates the separation efficiency of charge carriers. Moreover, the D–A structure plays an important role in adjusting the width of band gap, which can increase the light absorption capacity of the catalyst. The D–A system also leads to the formation of a built-in electric field, which significantly accelerates the migration speed of electrons. Among the prepared catalysts, g-CN-Bz (0.01) has the best photocatalytic CO₂ reduction performance, and the evolution rate of CO is 5.2 times higher than that of CN (3.64 μmol g⁻¹). In addition, the reaction is carried out in water without any sacrificial agent, which makes it green and environmentally friendly.

Graphic Abstract

The charge carrier excitation-recombination process between donor and acceptor, and photocatalytic reduction of CO₂ to CO over the CN based DA composites.

中文翻译：

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基于碳氮化物的分子内D–A体系的有效光催化还原CO 2的构建

光催化技术为缓解能源危机提供了新的策略。高效和稳定的可见光响应的光催化材料的开发一直是光催化领域研究者的方向。石墨氮化碳（g-CN）由于其特殊的特性（例如可见光响应，高稳定性和低成本）而在光催化领域引起了越来越多的关注。然而，光生电子和空穴的低分离效率限制了其催化活性。在本文中，准备了一种新型的基于g-CN的分子内供体-受体（D-A）系统，以提高光诱导电荷载体的分离效率。该催化剂由g-CN和1,2-二溴苯（Bz）通过简单的煅烧方法制备。表征结果证实Bz已成功引入g-CN（g-CN-Bz（x））框架。D–A结构的形成导致电子和空穴对的空间分离，这大大加快了电荷载流子的分离效率。此外，D–A结构在调节带隙宽度方面起着重要作用，可以增加催化剂的光吸收能力。D–A系统还导致形成内置电场，从而大大加快了电子的迁移速度。在制备的催化剂中，g-CN-Bz（0.01）具有最佳的光催化CO 这大大提高了电荷载流子的分离效率。此外，D–A结构在调节带隙宽度方面起着重要作用，可以增加催化剂的光吸收能力。D–A系统还导致形成内置电场，从而大大加快了电子的迁移速度。在制备的催化剂中，g-CN-Bz（0.01）具有最佳的光催化CO 这大大提高了电荷载流子的分离效率。此外，D–A结构在调节带隙宽度方面起着重要作用，可以增加催化剂的光吸收能力。D–A系统还导致形成内置电场，从而大大加快了电子的迁移速度。在制备的催化剂中，g-CN-Bz（0.01）具有最佳的光催化CO_2的还原性能，CO的释放速率比CN（3.64μmolg ^-1）高5.2倍。另外，该反应在没有任何牺牲剂的水中进行，这使其绿色环保。

图形摘要

供体和受体之间的电荷载流子激发-重组过程，以及在基于CN的DA复合材料上将CO ₂光催化还原为CO的过程。