Self-Assembled One-Dimensional Porphyrin Nanostructures with Enhanced Photocatalytic Hydrogen Generation

Abstract

There has been a widespread interest in the preparation of self-assembled porphyrin nanostructures and their ordered arrays, aiming to emulate natural light harvesting processes and energy storage and to develop new nanostructured materials for photocatalytic process. Here, we report controlled synthesis of one-dimensional porphyrin nanostructures such as nanorods and nanowires with well-defined self-assembled porphyrin networks that enable efficient energy transfer for enhanced photocatalytic activity in hydrogen generation. Preparation of these one-dimensional nanostructures is conducted through noncovalent self-assembly of porphyrins confined within surfactant micelles. X-ray diffraction and transmission electron microscopy results reveal that these one-dimensional nanostructures contain stable single crystalline structures with controlled interplanar separation distance. Optical absorption characterizations show that the self-assembly enables effective optical coupling of porphyrins, resulting in much more enhanced optical absorption in comparison with the original porphyrin monomers, and the absorption bands red shift to more extensive visible light spectrum. The self-assembled porphyrin network facilitates efficient energy transfer among porphyrin molecules and the delocalization of excited state electrons for enhanced photocatalytic hydrogen production under visible light.

A Full‐Spectrum Metal‐Free Porphyrin Supramolecular Photocatalyst for Dual Functions of Highly Efficient Hydrogen and Oxygen Evolution

“…It should be pointed out however, that in most of those studies, porphyrin was used as a dye to broaden the spectral response range of another host material but did not as a photocatalyst itself . In addition, the porphyrin‐based photocatalysts employed for photocatalytic water splitting have so far only been able to drive the 2‐electron half‐reaction, but not the 4‐electron water oxidation. Furthermore, the hydrogen evolution reaction on porphyrin has typically required the assistance of noble metal cocatalysts.…”

Hierarchical Self‐Assembly of Tetrakis(1‐pyrenyl)porphyrins into Microscopic Petals and Flowers with Ultrasensitive Room‐Temperature NO2 Sensing in a Broad Humidity Range

“…It is worth point that, unlike porphyrin‐based self‐assembled aggregates reported proviousely, we failed to get the X‐ray diffraction patterns of the aggregates of both 1 and 2 for further internal structure analysis, most probably because of the disorder (or the rotation) of the four bulky pyrenyl moieties in the porphyrin molecules at room temperature. This kind of disordered supermolecular stacking structure originating from hydrophobic pyrenyl moieties, combined with the corresponding special bio‐morphology, (nanopetals and micro‐“ball‐flower”), would provide sufficient active sites to interact with analytes, and thus contribute to the good sensing performance under a large relative humidity (RH) range.…”

Novel Supramolecular Photocatalyst Based on Conjugation of Cucurbit[7]uril to Non‐Metallated Porphyrin for Electrophotocatalytic Hydrogen Generation from Water Splitting

“…Due to its high molar absorptivity, dual‐absorption band feature and high charge carrier mobility, the electron migrations are believed to be facilitated, thus reducing the risks of photogenerated electron‐hole pairs recombination . In this regard, self‐assembled porphyrin derivatives in the form of nanoparticles, nanowires and nanorods as well as the composite of porphyrin‐based porous covalent organic framework with TiO 2 , porphyrin‐based imine gels and cobalt porphyrin‐polypyridyl surface coatings were utilized as visible‐light triggered photocatalysts in the hydrogen production from water splitting.…”

“…Due to its high molar absorptivity, dualabsorption band feature and high charge carrier mobility, the electron migrations are believed to be facilitated, thus reducing the risks of photogenerated electron-hole pairs recombination. [6b,c] In this regard, self-assembled porphyrin derivatives in the form of nanoparticles, nanowires and nanorods [9][10][11] as well as the composite of porphyrin-based porous covalent organic framework with TiO 2 [12] , porphyrinbased imine gels [13] and cobalt porphyrin-polypyridyl surface coatings [14] were utilized as visible-light triggered photocatalysts in the hydrogen production from water splitting.Herein, we report the synthesis of a novel photoactive supramolecular assembly that is based on the conjugation of cucurbit[7]uril hosts to free-base porphyrin core (TTP-4CB7) (Scheme 1) and also demonstrate the use of this assembly as a photocatalyst in hydrogen production from water splitting. Cucurbit[n]uril is a macrocycle and can be found in various sizes depending upon the number of glycol units which is composed of.…”