Self-assembled supramolecular nanostructure photosensitizers for photocatalytic hydrogen evolution

Supramolecular self-assembly as a breakthrough methodology in the nanoscience and nanotechnology fields has attracted increasing attention. Highly ordered self-assembled supramolecular nanostructures aim to emulate natural light-harvesting and energy transfer and electron transfer processes, which have been an active and rapidly developing field for visible-light-driven photocatalytic applications. This Research Update aims to present the recent progress of the self-assembly of π-conjugated molecules, including perylene diimides (PDIs), porphyrin, and co-assembly of peptide–porphyrin as well as the shape-defined functional hierarchical structures. First, the basic principles of π-conjugated molecular structure design are described. The two nitrogen positions and the bay positions of PDIs can effectively regulate their electronic properties and geometric skeleton, and the functional groups and the good solvents of porphyrin effectively determine the choice of self-assembly methods. Then, the key morphology dependent optoelectronic properties and charge-transport and energy-transport functionalities are also discussed. These self-assembled supramolecular nanostructures’ inherent optoelectronic properties correlated with applications in photocatalytic water splitting into hydrogen evolution are overviewed. By now, the self-assembled In(III) meso-tetraphenylporphine (InTPP) porphyrin nanostructures exhibited the highest photocatalytic hydrogen generation activity among the reported supramolecular nanostructures owing to the central metal of porphyrin and small size of the InTPP nanostructure. Finally, perspectives on the crucial issues and potential future research directions are addressed. This Research Update will provide a new reference for building high performance, stable, and durable photosensitizers based on the supramolecular assembly.