Nanostructured Lateral Boryl Substitution Conjugated Donor–Acceptor Oligomers for Visible‐Light‐Driven Hydrogen Production. Issue 23 (23rd April 2021)

• Record Type: Journal Article
• Authors: Wei, Qiuyu; Yao, Xiaoqiang; Zhang, Qianqian; Yan, Pengji; Ru, Chenglong; Li, Chunfeng; Tao, Chunlan; Wang, Wei; Han, Dongfang; Han, Dongxue; Niu, Li; Qin, Dongdong; Pan, Xiaobo
• Is Part Of: Small. Volume 17:Issue 23(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-04-23
• Subjects: boryl substitution -- donor–acceptor -- hydrogen generation -- nanosheets -- oligomer photocatalyst -- visible light; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202100132
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Poor charge separation is the main factor that limits the photocatalytic hydrogen generation efficiency of organic conjugated polymers. In this work, a series of linear donor–acceptor (D–A) type oligomers are synthesized by a palladium‐catalyzed Sonogashira–Hagihara coupling of electron‐deficient diborane unit and different dihalide substitution sulfur functionalized monomers. Such diborane‐based A unit exerts great impact on the resulting oligomers, including distinct semiconductor characters with isolated lowest unoccupied molecular orbital (LUMO) orbits locating in diborane‐containing fragment, and elevated LUMO level higher than water reduction potential. Relative to A‐A type counterpart, the enhanced dipole polarization effect in D–A oligomers facilitates separation of photogenerated charge carriers, as evidenced by notably prolonged electron lifetime. Owing to π–π stacking of rigid backbone, the oligomers can aggregate into an interesting 2D semicrystalline nanosheet (≈2.74 nm), which is rarely reported in linear polymeric photocatalysts prepared by similar carbon–carbon coupling reaction. Despite low surface area (30.3 m 2 g −1 ), such ultrathin nanosheet D–A oligomer offers outstanding visible light (λ > 420 nm) hydrogen evolution rate of 833 µmol g −1 h −1, 14 times greater than its A‐A analogue (61 µmol g −1 h −1 ). The study highlights the great potential of using boron element to construct D–A type oligomers for efficient photocatalytic hydrogen generation. Abstract : Diborane group has been explored to construct donor–acceptor type conjugated polymers for visible‐light‐driven photocatalytic hydrogen generation. The resulting polymers aggregate into semicrystalline ultrathin nanosheets and exhibit distinct semiconductor features. The improved charge separation and interfacial charge transfer result in a good hydrogen evolution rate of 833 μmol g ‐1 h ‐1, outperforming most of linear polymers with thiophene as donor group.