Controlling photocatalytic activity by self-assembly – Tuning perylene bisimide photocatalysts for the hydrogen evolution reaction

Daniel McDowall, Benjamin J. Greeves, Rob Clowes, Kate McAulay, Ana M. Fuentes-Caparrós, Lisa Thomson, Nikul Khunti, Nathan Cowieson, Michael C. Nolan, Matthew Wallace, Andrew I. Cooper, Emily R. Draper, Alexander J. Cowan, Dave J. Adams

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Abstract

Amino acid functionalized perylene bisimides (PBIs) form self-assembled structures in solution, the nature of which depends on the local environment. Using a high-throughput photocatalysis setup, five PBIs are studied for the hydrogen evolution reaction (HER) under a range of conditions (pH and hole scavenger concentration) across 350 experiments to explore the relationship between supramolecular structure and photocatalytic activity. Using small angle X-ray scattering (SAXS), NMR spectroscopy and ultraviolet-visible (UV-vis) absorption spectroscopy, it is shown that photocatalytic activity is determined by the nature of the self-assembled aggregate that is formed, demonstrating the potential of self-assembly to tune activity. There is a clear correlation between the presence of charged flexible cylindrical aggregates and the occurrence of photocatalytic H2 production, with UV–vis spectroscopy indicating that the most active structure type has a distinctive form of π-aggregation which is proposed to enable efficient charge separation across multiple PBI units.

Original languageEnglish
Article number2002469
JournalAdvanced Energy Materials
Volume10
Issue number46
Early online date26 Oct 2020
DOIs
Publication statusPublished - 8 Dec 2020

Keywords

  • hydrogen
  • organic photocatalysts
  • self-assembly
  • solar fuels

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