Molecular structure regulation through bay-substitution with chlorine to enhance the photocatalytic H2 production of perylene tetracarboxylic acid-based supramolecular photocatalyst

Abstract

Supramolecular photocatalyst based on organic small molecules containing planar perylene ring cores have become promising organic photocatalysts due to the formation of electron migration channels through the π-π stacking effects. Herein, two kinds of non-covalent self-assembled supramolecular photocatalysts PTA and Cl-PTA were synthesized through hydrolysis-acidification process and the aggregation properties were regulated by the concentration of acid in the assembly process. So the effects of assemblies properties and the molecular structures regulation on the photocatalytic hydrogen production activity were investigated. The optimized PTA 0 M and Cl-PTA 3.6 M assemblies showed the hydrogen production rates of 15.2 mmol h⁻¹ g⁻¹ and 27.1 mmol h⁻¹ g⁻¹ respectively. The substitution of the electron-withdrawing group chlorine at the bay site of PTA can regulate the electron distribution and band structure of the molecule and promote the transfer of photogenerated charge carriers, which is favorable for the photocatalytic hydrogen evolution reaction. Therefore, the hydrogen evolution rate of supramolecular catalyst can be effectively improved by reasonable molecular structure modification strategy.