Conjugated Polymers with Sequential Fluorination for Enhanced Photocatalytic H₂ Evolution via Proton-Coupled Electron Transfer

Abstract

The performance of donor–acceptor (D–A) conjugated polymer-based photocatalyts for solar hydrogen production is severely limited by poor charge mobility and weak reactive sites. Here, a series of D–A conjugated polymers with electronegative fluorine atoms on the backbone is presented and the influence of fluorination on charge transfer and catalytic site activity is investigated. Theoretical calculation reveals that sequential fluorination on the A unit benzothiadiazole will activate the catalytic site, and the photocatalytic H2 generation process could be illustrated by a proton-coupled electron-transfer mechanism. Two series of fluorinated polymers were synthesized, and accelerated charge transfer was also verified. Among them, linear B-FOBT-1,4-E and porous B-FOBT-1,3,5-E with simultaneous electron-donating CH3O– and electron-withdrawing F-substitution show a H2 evolution rate that is 3.1 and 28.8 times higher than that of nonfluorinated counterparts, respectively, and the apparent quantum yield of 5.7% at 420 nm is obtained for B-FOBT-1,4-E. The results provide reciprocal understanding of the activation nature of substituent-regulating polymers.

Intermolecular cascaded π-conjugation channels for electron delivery powering CO2 photoreduction

“…Cyclic voltammetry (CV) measurements were also conducted, the highest occupied molecular orbital (HOMO) position can be determined by the irreversibility of the oxidation peaks because the irreversible oxidation process of the CPs at the impressed voltage (Supplementary Fig. 10) revealed different energy levels within the CPs (Supplementary Table 1) 39 . In addition, their energy levels were further investigated by the ultraviolet photoelectron spectroscopy (UPS) ( Supplementary Fig.…”

Recent Advances in Visible‐Light‐Driven Hydrogen Evolution from Water using Polymer Photocatalysts

“…Similarly, they also prepared a series of D-A-based linear polymers containing benzothiadiazole (BT) building units and studied the effects of substitution on the catalytic activity and the charge transfer of the polymers in water splitting. [23] In particular, highly substituted polymer BÀ FOBT-1,4-E showed a high HER of 13,300 μmol h À 1 g À 1 and AQY of 5.7 % at 420 nm compared to those of unsubstituted polymer BÀ BT-1,4-E with a sacrificial donor. These results clearly showed that the introduction of methoxy (OMe) groups or a number of fluorine (n = 0-2F, F/OCH 3 ) atoms onto BT units can have a significant impact in photocatalytic reactions.…”

“…Surprisingly, the active polymer P7‐E exhibited a high HER of 6,023 μmol h −1 g −1 , with a low AQY of 4.2 % at 420 nm, compared to those of other P7 polymers under visible light even without the addition of Pt as a cocatalyst (see Table ). Similarly, they also prepared a series of D‐A‐based linear polymers containing benzothiadiazole (BT) building units and studied the effects of substitution on the catalytic activity and the charge transfer of the polymers in water splitting . In particular, highly substituted polymer B−FOBT‐1,4‐E showed a high HER of 13,300 μmol h −1 g −1 and AQY of 5.7 % at 420 nm compared to those of unsubstituted polymer B−BT‐1,4‐E with a sacrificial donor.…”

Photocatalysts Based on Organic Semiconductors with Tunable Energy Levels for Solar Fuel Applications

“…[29] Similar studies also reflect this, whereby the measured surface area showed no relationship to photocatalytic activity. [33,[103][104][105][106][107] Figure 5. Cryo-transmission electron microscopy images of NP HEPs formed from a 3:7 blend of the polymer PTB7-Th (12) and the nonfullerene acceptor EH-IDTBR (13) with 10 wt% photodeposited Pt cocatalyst after 20 h H 2 evolution.…”