Synergistic Contribution of Oligo(ethylene glycol) and Fluorine Substitution of Conjugated Polymer Photocatalysts toward Solar Driven Sacrificial Hydrogen Evolution. Issue 5 (29th November 2022)

• Record Type: Journal Article
• Authors: An, Sanghyeok; Wu, Ziang; Jeong, Hayoung; Lee, Juhyeok; Jeong, Sang Young; Lee, Wonjong; Kim, Sunkyu; Han, Jeong Woo; Lim, Jongchul; Cha, Hyojung; Woo, Han Young; Chung, Dae Sung
• Is Part Of: Small. Volume 19:Issue 5(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-29
• Subjects: hydrogen evolution -- photocatalysts -- polymer semiconductors -- water‐splitting; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202204905
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: To separately explore the importance of hydrophilicity and backbone planarity of polymer photocatalyst, a series of benzothiadiazole‐based donor–acceptor alternating copolymers incorporating alkoxy, linear oligo(ethylene glycol) (OEG) side chain, and backbone fluorine substituents is presented. The OEG side chains in the polymer backbone increase the surface energy of the polymer nanoparticles, thereby improving the interaction with water and facilitating electron transfer to water. Moreover, the OEG‐attached copolymers exhibit enhanced intermolecular packing compared to polymers with alkoxy side chains, which is possibly attributed to the self‐assembly properties of the side chains. Fluorine substituents on the polymer backbone produce highly ordered lamellar stacks with distinct π–π stacking features; subsequently, the long‐lived polarons toward hydrogen evolution are observed by transient absorption spectroscopy. In addition, a new nanoparticle synthesis strategy using a methanol/water mixed solvent is first adopted, thereby avoiding the screening effect of surfactants between the nanoparticles and water. Finally, hydrogen evolution rate of 26 000 µmol g −1 h −1 is obtained for the copolymer incorporated with both OEG side chains and fluorine substituents under visible‐light irradiation (λ > 420 nm). This study demonstrates how the glycol side chain strategy can be further optimized for polymer photocatalysts by controlling the backbone planarity. Abstract : A case study to simultaneously understand the correlation between the molecular design of conjugated polymers and exciton separation/charge transfer characteristics for hydrogen evolution is reported. It is shown that though introducing hydrophilic side chain is clearly helpful for exciton separation, backbone planarity is further required to realize successful transfer of once separated electrons to protons and holes to scavengers.