Zhou Enbo, Zhang Xiang, Zhu Lei, Chai Erchong, Chen Jinsong, Li Jie, Yuan Daqiang, Kang Longtian, Sun Qingfu, Wang Yaobing
CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002 Fujian, P. R. China.
University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
Sci Adv. 2024 Jan 19;10(3):eadk8564. doi: 10.1126/sciadv.adk8564. Epub 2024 Jan 17.
Photocatalytic water oxidation is a key half-reaction for various solar-to-fuel conversion systems but requires simultaneous water affinity and hole accumulation at the photocatalytic site. Here, we present the rational design and synthesis of an ionic-type covalent organic framework (COF) named tetraphenylporphyrin cobalt and cobalt bipyridine complex (CoTPP-CoBpy) COF, combining cobalt porphyrin and cobalt bipyridine building blocks as a photocatalyst for water oxidation. The good dispersibility of porous large-size (>2 micrometers) COF nanosheets (≈1.45 nanometers) facilitates local water collection; the ultrafast triplet-state charge transfer (1.8 picoseconds) and prolonged charge separation (1.2 nanoseconds) further contribute to the efficient accumulation of holes in the CoTPP moiety, leading to a photocatalytic dioxygen production rate of 7323 micromoles per gram per hour. Moreover, we have identified an end-on superoxide radical (O) intermediate at the active site of the CoTPP moiety and proposed an electron-intermediate cascade mechanism that elucidates the synergistic coupling of electron relay (S-T-T') and intermediate evolution during the photocatalytic process.
光催化水氧化是各种太阳能到燃料转换系统的关键半反应，但需要在光催化位点同时具备水亲和力和空穴积累。在此，我们展示了一种名为四苯基卟啉钴和钴联吡啶配合物（CoTPP-CoBpy）COF的离子型共价有机框架（COF）的合理设计与合成，它将钴卟啉和钴联吡啶结构单元结合起来作为水氧化的光催化剂。多孔大尺寸（>2微米）COF纳米片（≈1.45纳米）的良好分散性有助于局部水的收集；超快的三重态电荷转移（1.8皮秒）和延长的电荷分离（1.2纳秒）进一步促进了空穴在CoTPP部分的有效积累，导致光催化产氧速率为每克每小时7323微摩尔。此外，我们在CoTPP部分的活性位点鉴定出一种端基超氧自由基（O）中间体，并提出了一种电子中间体级联机制，该机制阐明了光催化过程中电子中继（S-T-T'）和中间体演化的协同耦合。
