Modulation of Self-Assembly and Enhanced Photocatalytic H₂ Production by Porphyrin-Dipeptide Conjugates

Herein, it is reported the visible-light-induced green hydrogen generation from self-assembled porphyrin-dipeptide hybrids. For the first time the self-assembly ability of a protected alanine-phenylalanine dipeptide is investigated via a simple protocol, which proved efficient in forming well-defined fibrillar architectures. These self-assembling properties are conveyed to peptide-porphyrin chromophores after their covalent conjugation. Interestingly, different architectures are observed depending on the solvent system, the solvent evaporation rate, the presence of metal in the porphyrin core, and the peripheral substitution of the porphyrin. Moving one step forward, it is explored the activity of the self-assembled nanostructures towards photocatalytic green H₂ production from aqueous protons under visible-light irradiation. The distinct self-assembly behavior of the synthesized conjugates and their impact on photocatalytic hydrogen production is systematically explored in this study. Nonlinear second harmonic generation optical measurements are employed to define how the shape of the nanostructures is related to the H₂ production efficiency. Notably, the tubular nanostructures presented the best catalytic performance, achieving a high H₂ production activity of 32.7 mmol·g^-1·h^-1. Through detailed characterization and performance evaluation, it is aimed to uncover new insights into the design and optimization of peptide-porphyrin-based photocatalysts for sustainable energy applications.