Gelation enabled charge separation following visible light excitation using self-assembled perylene bisimides

Abstract

Perylene bisimides (PBIs) can be functionalised to enable controlled aggregation into complex supramolecular structures and are promising materials for photovoltaic and solar fuel applications.

Controlling Photocatalytic Activity by Self‐Assembly – Tuning Perylene Bisimide Photocatalysts for the Hydrogen Evolution Reaction

“…Recent spectroscopic studies on related PBI‐A hydrogel films and pH 9 solutions indicate that hole transfer can occur via the alanine group and this may also be occurring here prior to methanol oxidation. [ 33 ] Electron transfer to the Pt co‐catalyst from the PBI structures can then occur, enabling H 2 production. Electrochemical measurements show that H 2 evolution is thermodynamically feasible following electron transfer from the singly (PBI ○− ) and doubly reduced (PBI 2− ) species below pH 8 (PBI ○− ) and pH 7 (PBI 2− ) for PBI‐A, and below pH 7 (PBI ○− ) and pH 6 (PBI 2− ) for PBI‐Y, (Section S4.2, Supporting Information).…”

“…Considerably less H 2 is formed when there is no methanol present; this confirms the importance of the sacrificial electron donor indicating that in the absence of methanol the fast carrier recombination occurs preventing photoelectron transfer to the Pt co‐catalyst, in agreement with past transient absorption studies on related systems. [ 33 ] The low‐levels of H 2 seen at 0 v/v may indicate that in the absence of an electron donor complete water splitting can occur or more likely that self‐oxidation of the photocatalyst can take place under these conditions. The maximum H 2 evolved occurred at 30 v/v methanol concentration; however, we do not see a simple trend for increased H 2 evolution with methanol concentration and a local maximum in H 2 production is observed around 5–10 v/v as well (Figure 4).…”

“…[ 31,32 ] The application of hydrogels and aqueous solvated self‐assembled materials to photocatalysis is particularly interesting as we have recently shown that the solvent environment enables charge separation, overcoming a known limitation of many other organic photocatalysts with inherently low dielectric constants. [ 33 ]…”

“…[31,32] The application of hydrogels and aqueous solvated self-assembled materials to photocatalysis is particularly interesting as we have recently shown that the solvent environment enables charge separation, overcoming a known limitation of many other organic photocatalysts with inherently low dielectric constants. [33] Stupp's group has shown a range of self-assembled PMIs can be effective as part of a photocatalytic hydrogen evolution reaction (HER). [20,[34][35][36] Recently, they have also published work studying hybrid polyelectrolyte and supramolecular systems in which PMIs are entrapped in a crosslinked polyelectrolyte hydrogel.…”

Controlling Activity by Self-Assembly – Tuning Perylene Bisimide Photocatalysts for the Hydrogen Evolution Reaction

“…28,29 The application of hydrogels and aqueous solvated self-assembled materials to photocatalysis is particularly interesting as we have recently shown that the solvent environment enables charge separation, overcoming a known limitation of many other organic photocatalysts with inherently low dielectric constants. 30 Stupp's group has shown a range of self-assembled PMIs can be effective as part of a photocatalytic hydrogen evolution reaction (HER). 17,[31][32][33] Recently, they have also published work studying hybrid polyelectrolyte and supramolecular systems in which PMIs are entrapped in a crosslinked polyelectrolyte hydrogel.…”