Morphology-controlled porphyrin nanocrystals with enhanced photocatalytic hydrogen production

Molecular self-assembly is a natured-inspired strategy to integrate individual functional molecules into supramolecular nanostructured materials through noncovalent bond interactions for solar to fuel conversion. However, the design and engineering of the morphology, size, and orderly stacking of supramolecular nanostructures remain a great challenge. In this study, regular porphyrin nanocrystals with different orderly stacked structures are synthesized through noncovalent self-assembly of Pt(II) meso-tetra (4-carboxyphenyl) porphine (PtTCPP), using surfactants with different electronegativity. The synergy of noncovalent bond interactions between porphyrin molecules, and between porphyrin molecules and surfactants resulted in different molecular packing patterns. Due to the spatial ordering of PtTCPP molecules, the different nanocrystals exhibit both collective optical properties and morphology-dependent activities in photocatalytic hydrogen production. The measurements of the photodeposition of dual cocatalysts showed that the photogenerated electrons and holes selectively aggregated at different active sites, revealing separation pathways and directional transfer of photogenerated electrons and holes in the assemblies. This study provides a new strategy to exert rational control over porphyrin self-assembly nanocrystals for highly efficient water splitting.