Effect of Axial Coordination of Iron Porphyrin on Their Nanostructures and Photocatalytic Performance

Abstract

Enough exposure of an active face is a key factor of nanocatalysis for sustainable energy conversion. Here, we exhibit the effect of axial coordination of organic metal complex molecules on the morphology evolution and photocatalytic hydrogen evolution (PHE) activity of organic nanocrystals (ONCs). The three series of iron porphyrin (FeTPPX, X = Cl, O, and OH) ONCs are controllably synthesized via the cetyltrimethylammonium bromide (CTAB)-assisted chemical reaction at different pH values. The uniform zero-dimensional FeTPPCl ONCs, ultrafine one-dimensional [FeTPP] 2 O ONCs with a diameter of ∼35 nm, and ultrathin two-dimensional FeTPPOH•H 2 O ONCs with the thickness of a crystal cell (<1 nm) can be obtained by adjusting the concentration and volume of CTAB during the hydrolysis reaction of iron porphyrin perchlorate (FeTPP•ClO 4 ). The mechanism of morphology evolution is carefully investigated, revealing the synergistic effect of the axial ligand of FeTPPX and CTAB on the exposure of the hydrophilic active face parallel to the porphyrin ring. Size-, shape-, and axial ligand-dependent photocatalysis can be clearly observed. Without using a cocatalyst, the FeTPPOH•H 2 O ultrathin nanoflakes display the highest PHE rate (∼0.75 mmol/h/g), followed by FeTPPCl octahedrons (∼0.48 mmol/h/g) and [FeTPP] 2 O ultrafine nanorods (∼0.20 mmol/h/g). This work provides a new strategy to apply the conjugated organic compounds in nanocatalysis.

Porphyrins and phthalocyanines as biomimetic tools for photocatalytic H2production and CO2reduction

“…Another approach from the same research team utilized again a metallated tetra-phenyl porphyrin and the CTAB surfactant. 69 In detail they used iron porphyrin perchlorate (FeTPPÁClO 4 ) to prepare organic nanocrystals (ONCs) via the hydrolysis of FeTPPÁClO 4 in the presence of CTAB. They achieved to prepare uniform and regular 0-dimensional FeTPP-Cl, ultrafine 1 dimensional [FeTPP] 2 O and ultrathin 2D FeTPP-OH H 2 O ONCs by tuning the pH, and the concentrations of the monomer and of CTAB.…”

Monitoring the Hierarchical Evolution from a Double-Stranded Helix to a Well-Defined Microscopic Morphology Based on a Turbine-like Aromatic Molecule

“…These π conjugated systems are of particular interest not only for the predictability of their self-assembled nanostructures but also because of the tunability of self-assembled nanostructures as a result of the stimuli-responsiveness of substituents. 12 Moreover, the features of π-conjugated building blocks provide wide potential applications such as optoelectronic devices, organic semiconductors, photocatalysis, and sensors for their different dimensional nanostructures. 13 Because of the above-mentioned advantages, branched aromatic molecules with immobilized conformation provide a potential platform for the construction of supramolecular helical configuration and further exploration of the secondary assembly behavior of obtained helices based on theoretical simulation and imaging technique.…”

“…This is owing to the intrinsic tropism of π–π stacking in architectures and the supplement of other driving forces such as hydrogen bonds, hydrophobic and coordination interactions, and electrostatic interactions between their alterable substituents. These π conjugated systems are of particular interest not only for the predictability of their self-assembled nanostructures but also because of the tunability of self-assembled nanostructures as a result of the stimuli-responsiveness of substituents . Moreover, the features of π-conjugated building blocks provide wide potential applications such as optoelectronic devices, organic semiconductors, photocatalysis, and sensors for their different dimensional nanostructures .…”

Structure, Properties, and Reactivity of Porphyrins on Surfaces and Nanostructures with Periodic DFT Calculations

“…As mentioned earlier, PDFT studies of x-ray crystal structures of porphyrins are rare. Some of the other studies include determination of surface free energy of different crystal faces of FeTPPCl (TPP = tetra-phenyl porphyrin) and FeTPPOH•H 2 O nanocrystals by Tian et al [50]. They used PDFT calculated surface energies of {001}, {100}, {110}, {011} crystal faces to understand and tune the growth and shape of the FeTPP based nanocrystals.…”