Effect of the length of bromoalkyl chains on light-driven hydrogen evolution facilitated by fluorene-based polymers

Six fluorene-based polymers are designed, synthesized, characterized, and examined in light-driven hydrogen evolution. The relationship of the hydrogen-evolution activity with the optical/electronic characteristics of the polymers is insignificant, suggesting that it might not be the most crucial factor in distinguishing the efficiency. Polymers with shorter bromoalkyl chains exhibit greater hydrogen evolution rates (HERs) than their analogues with longer chains, highlighting the significance of chain length in the reaction. The role of residual Pd as a co-catalyst is investigated. The HER is improved substantially by the presence of Pd. A high HER of 42 mmol g −1 h −1 , which is among the highest reported to date, has been achieved. Overall, this work demonstrates that side-chain truncation and modification serve as a straightforward approach to improving the hydrogen-evolution activity. Tetraalkylammonium bromide is produced in situ . The effect of the length of bromoalkyl chains is recognized, indicating the importance of side-chain engineering. The hydrogen evolution rate is improved significantly by the presence of Pd.