Covalent organic frameworks (COFs) have recently shown great potential for photocatalytic hydrogen production. Currently almost all reports are focused on two‐dimensional (2D) COFs, while the 3D counterparts are rarely explored due to their non‐conjugated frameworks derived from the sp3 carbon based tetrahedral building blocks. Here, we rationally designed and synthesized a series of fully conjugated 3D COFs by using the saddle‐shaped cyclooctatetrathiophene derivative as the building block. Through molecular engineering strategies, we thoroughly discussed the influences of key factors including the donor‐acceptor structure, hydrophilicity, specific surface areas, as well as the conjugated/non‐conjugated structures on their photocatalytic hydrogen evolution properties. The as‐synthesized fully conjugated 3D COFs could generate the hydrogen up to 40.36 mmol h‐1 g‐1. This is the first report on intrinsic metal‐free 3D COFs in photocatalytic hydrogen evolution application. Our work provides insight on the structure design of 3D COFs for highly‐efficient photocatalysis, and also reveals that the semiconducting fully conjugated 3D COFs could be a useful platform in clear energy‐related fields.

中文翻译：

---

调节全共轭 3D 共价有机框架光催化析氢的分子工程

共价有机框架（COF）最近在光催化制氢方面显示出巨大的潜力。目前，几乎所有报告都集中在二维 (2D) COF，而 3D 对应物很少被探索，因为它们的非共轭框架源自 sp3 碳基四面体构件。在这里，我们以鞍形环辛四噻吩衍生物为构建单元，合理设计并合成了一系列完全共轭的3D COF。通过分子工程策略，我们深入讨论了供体-受体结构、亲水性、比表面积以及共轭/非共轭结构等关键因素对其光催化析氢性能的影响。合成的完全共轭的 3D COF 可以产生高达 40.36 mmol h-1 g-1 的氢。这是关于本征无金属 3D COF 在光催化析氢应用中的第一份报告。我们的工作为高效光催化的 3D COF 的结构设计提供了见解，并揭示了半导体全共轭 3D COF 可能成为清洁能源相关领域的有用平台。