Issue 6, 2020

Side-chain tuning in conjugated polymer photocatalysts for improved hydrogen production from water

Abstract

Structure–property–activity relationships in solution processable polymer photocatalysts for hydrogen production from water were probed by varying the chemical structure of both the polymer side-chains and the polymer backbone. In both cases, the photocatalytic performance depends strongly on the inclusion of more polar groups, such as dibenzo[b,d]thiophene sulfone backbone units or oligo(ethylene glycol) side-chains. We used optical, spectroscopic, and structural characterisation techniques to understand the different catalytic activities of these systems. We find that although polar groups improve the wettability of the material with water in all cases, backbone and side-chain modifications affect photocatalytic performance in different ways: the inclusion of dibenzo[b,d]thiophene sulfone backbone units improves the thermodynamic driving force for hole transfer to the sacrificial donor, while the inclusion of oligo ethylene glycol side-chains aids the degree of polymer swelling and also extends the electron polaron lifetime. The best performing material, FS-TEG, exhibits a HER of 72.5 μmol h−1 for 25 mg photocatalyst (2.9 mmol g−1 h−1) when dispersed in the presence of a sacrificial donor and illuminated with λ > 420 nm light, corresponding to a hydrogen evolution EQE of 10% at 420 nm. When cast as a thin film, this HER was further boosted to 13.9 mmol g−1 h−1 (3.0 mmol m−2 h−1), which is among the highest rates in this field.

Graphical abstract: Side-chain tuning in conjugated polymer photocatalysts for improved hydrogen production from water

Supplementary files

Article information

Article type
Paper
Submitted
17 Apr 2020
Accepted
07 May 2020
First published
07 May 2020
This article is Open Access
Creative Commons BY license

Energy Environ. Sci., 2020,13, 1843-1855

Side-chain tuning in conjugated polymer photocatalysts for improved hydrogen production from water

D. J. Woods, S. A. J. Hillman, D. Pearce, L. Wilbraham, L. Q. Flagg, W. Duffy, I. McCulloch, J. R. Durrant, A. A. Y. Guilbert, M. A. Zwijnenburg, R. S. Sprick, J. Nelson and A. I. Cooper, Energy Environ. Sci., 2020, 13, 1843 DOI: 10.1039/D0EE01213K

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