Grafted Groups’ Modification in the Main Chain of Polyfluorene‐Based Conjugated Polyelectrolytes to Greatly Boost Solar Hydrogen Production from Natural Seawater

Abstract

Hydrogen represents an ideal fuel with environmental‐friendly properties and high energy density. It is attractive to directly produce clean hydrogen from inexhaustible solar energy and the most abundant seawater on the earth. Nevertheless, the search for highly efficient and stable photocatalysts remains a big challenge so far because of the dissolved salts in natural seawater, which may result in the decomposition of photocatalysts and undesirable side reactions. Herein, three polyfluorene‐based conjugated polyelectrolytes (CPEs) with different grafted groups in the polymer backbone for hydrogen production in natural seawater under solar light illumination are reported. The change in the grafted groups on the main chain of CPEs provides them very similar UV light absorption, but PFNH‐Br grafted with H group exhibits significantly improved charge transport and lower emission intensity compared with PFN‐Br (grafted with C8H17) and PFPABr (grafted with CH2CH2N(CH3)3Br). As a result, PFNH‐Br yield the highest hydrogen evolution rate (HER) of 1806 μmol h−1 g−1 without external cocatalysts under simulated solar light, while lower HERs of 356 and 225 μmol h−1 g−1 are found for PFN‐Br and PFPABr, respectively. This study shows that grafted group optimization is a powerful strategy to maximize the activity of polyfluorene‐based CPEs for direct photocatalytic seawater splitting.

Light-Powered Directional Ion Transport via PFN-Br/MoS2 Heterogeneous Membranes: Band Alignment and Activation Energy Barrier Engineering

“…Photoluminescence (PL) spectroscopy was performed to further confirm the charge transfer dynamics between PFN-Br and MoS 2 . As shown in Figure b, the pristine PFN-Br spectrum displays intense peaks at 433 and 455 nm, consistent with those from previous studies. ,− Furthermore, the incorporation of MoS 2 below the PFN-Br sample results in noticeable PL quenching, indicating reduced electron–hole recombination. , Considering the large light-driven ionic current in the system, the ion flux is thought to greatly increase with the irradiation. As shown in Figure S16, the ionic conductance of PB/MoS 2 M is facilitated by light illumination and is considerably boosted at concentrated KCl solutions.…”

Photocatalytic seawater splitting for hydrogen fuel production: impact of seawater components and accelerating reagents on the overall performance

“…The H incorporation in the CPE, PFNH-Br, which has the highest HER, allows for intermolecular p-p stacking and transport of charge. 112…”