To cope with the increasingly global greenhouse effect and energy shortage, it is urgent to develop a feasible means to convert anthropogenic excess carbon dioxide (CO₂) into energy resources. The photocatalytic CO₂ reduction reaction (CO₂RR) coupled with the water oxidation reaction (WOR), known as artificial photosynthesis, is a green, clean, and promoting strategy to deal with the above issues. Among the reported photocatalytic systems for CO₂ reduction, the main challenge is to achieve WOR simultaneously due to the limited charge separation efficiency and complicated dynamic process. To address the problem, scientists have assembled two nanosemiconductor motifs for CO₂RR and WOR into a heterojunction photocatalyst to realize artificial photosynthesis. However, it is difficult to clearly explore the corresponding catalytic mechanism and establish an accurate structure–activity relationship at the molecular level for their aperiodic distribution and complicated structural information. Standing on the shoulders of the heterojunction photocatalysts, a new-generation material, hetero-motif molecular junction (HMMJ) photocatalysts, has been developed and studied by our laboratory. A hetero-motif molecular junction is a class of crystalline materials with a well-defined and periodic structure, adjustable assembly mode, and semiconductor-like properties, which is composed of two predesigned motifs with oxidation and reduction, respectively, by coordination or covalent bonds. The intrinsic properties make these catalysts susceptible to functional modifications to improve light absorption and electrical conductivity. The small size and short distance of the motifs can greatly promote the efficiency of photogenerated electron–hole separation and migration. Based on these advantages, they can be used as potential excellent photocatalysts for artificial photosynthesis. Notably, the explicit structural information determined by single-crystal or powder X-ray diffraction can provide a visual platform to explore the reaction mechanism. More importantly, the connection number, spatial distance, interaction, and arrangement mode of the structural motifs can be well-designed to explore the detailed structure–activity relationship that can be hardly studied in nanoheterojunction photocatalyst systems. In this regard, HMMJ photocatalysts can be a new frontier in artificial photosynthesis and serve as an important bridge between molecular photocatalysts and solid photocatalysts. Thus, it is very important to summarize the state-of-the-art of the HMMJ photocatalysts used for artificial photosynthesis and to give in-depth insight to promote future development.

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异基序分子连接光催化剂：人工光合作用的新领域

为了应对日益严重的全球温室效应和能源短缺，迫切需要开发一种可行的手段将人为过量的二氧化碳(CO ₂ )转化为能源。光催化CO ₂还原反应(CO ₂ RR)与水氧化反应(WOR)耦合的人工光合作用是解决上述问题的一种绿色、清洁、可推广的策略。在已报道的用于CO ₂还原的光催化系统中，由于有限的电荷分离效率和复杂的动态过程，主要的挑战是同时实现WOR。为了解决这个问题，科学家们将CO ₂ RR和WOR的两种纳米半导体基序组装成异质结光催化剂，以实现人工光合作用。然而，由于它们的非周期性分布和复杂的结构信息，很难清楚地探索相应的催化机制并在分子水平上建立准确的构效关系。本实验室站在异质结光催化剂的肩膀上，开发和研究了新一代材料——异质基体分子结（HMMJ）光催化剂。异质基序分子结是一类具有明确的周期性结构、可调节的组装模式和类半导体特性的晶体材料，由两个预先设计的基序通过配位或共价键分别进行氧化和还原而组成。这些催化剂的固有特性使得它们易于进行功能修饰以提高光吸收和电导率。基序的小尺寸和短距离可以极大地提高光生电子空穴分离和迁移的效率。基于这些优点，它们可以作为潜在的优良光催化剂用于人工光合作用。值得注意的是，通过单晶或粉末X射线衍射确定的明确结构信息可以为探索反应机理提供可视化平台。更重要的是，可以精心设计结构基序的连接数量、空间距离、相互作用和排列方式，以探索纳米异质结光催化剂系统中难以研究的详细构效关系。在这方面，HMMJ光催化剂可以成为人工光合作用的新前沿，并成为分子光催化剂和固体光催化剂之间的重要桥梁。因此，总结用于人工光合作用的HMMJ光催化剂的最新技术并为促进未来的发展提供深入的见解非常重要。