Performance and Solution Structures of Side‐Chain‐Bridged Oligo (Ethylene Glycol) Polymer Photocatalysts for Enhanced Hydrogen Evolution under Natural Light Illumination

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 20; no. 6; pp. e2304743 - n/a
• Main Authors: Huang, Tse‐Fu, Liu, Jia‐Jen, Lai, Ze‐Yu, Chang, Je‐Wei, Zhuang, Ying‐Rang, Jiang, Zi‐Cheng, Chang, Chih‐Li, Lin, Wei‐Cheng, Chen, Yan‐Heng, Wu, Yi‐Hsiang, Sun, Yu‐En, Luo, Ting‐An, Chen, Yi‐Kuan, Yen, Jui‐Chen, Hsu, Hung‐Kai, Chen, Bo‐Han, Ting, Li‐Yu, Lu, Chia‐Yeh, Lin, Yu‐Tung, Hsu, Ling‐Yu, Wu, Tien‐Lin, Yang, Shang‐Da, Su, An‐Chung, Jeng, U‐Ser, Chou, Ho‐Hsiu
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.02.2024
• Subjects: Absorption spectra; Aqueous solutions; Carbazoles; Electron transfer; Ethylene glycol; Fractal geometry; Hydrogen; Hydrogen evolution; Illumination; Nanoclusters; Natural lighting; Nucleation; Photocatalysis; Photocatalysts; photocatalytic hydrogen evolution; Polyethylene glycol; Polymers; Seawater; side‐chain‐bridged conjugated polymers; Small angle X ray scattering; small‐angle and wide‐angle X‐ray scattering; Solar energy conversion; transient absorption spectroscopy; side-chain-bridged conjugated polymers; small-angle and wide-angle X-ray scattering; photocatalytic hydrogen evolution; ethylene glycol; transient absorption spectroscopy
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202304743

Converting solar energy into hydrogen energy using conjugated polymers (CP) is a promising solution to the energy crisis. Improving water solubility plays one of the critical factors in enhancing the hydrogen evolution rate (HER) of CP photocatalysts. In this study, a novel concept of incorporating hydrophilic side chains to connect the backbones of CPs to improve their HER is proposed. This concept is realized through the polymerization of carbazole units bridged with octane, ethylene glycol, and penta‐(ethylene glycol) to form three new side‐chain‐braided (SCB) CPs: PCz2S‐OCt, PCz2S‐EG, and PCz2S‐PEG. Verified through transient absorption spectra, the enhanced capability of PCz2S‐PEG for ultrafast electron transfer and reduced recombination effects has been demonstrated. Small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) analyses reveal that these three SCB‐CPs form cross‐linking networks with different mass fractal dimensions (f) in aqueous solution. With the lowest f value of 2.64 and improved water/polymer interfaces, PCz2S‐PEG demonstrates the best HER, reaching up to 126.9 µmol h−1 in pure water‐based photocatalytic solution. Moreover, PCz2S‐PEG exhibits comparable performance in seawater‐based photocatalytic solution under natural sunlight. In situ SAXS analysis further reveals nucleation‐dominated generation of hydrogen nanoclusters with a size of ≈1.5 nm in the HER of PCz2S‐PEG under light illumination. Pioneer examples of side‐chain‐bridged polymer photocatalysts, of tunable hydrophilicity of the side chains are presented. These polymers are capable of generating hydrogen using natural sunlight in seawater‐based photocatalytic solution. The distinctive structural characteristics and impressive HER performance of the side‐chain‐bridged conjugated polymers suggest a potential avenue in the development of photocatalytic conjugated polymers.