Biomimetic Approach toward Visible Light-Driven Hydrogen Generation Based on a Porphyrin-Based Coordination Polymer Gel

Abstract

There has been a widespread interest in developing selfassembled porphyrin nanostructures to mimic nature's light-harvesting processes. Herein, porphyrin-based coordination polymer gel (CPG) has been developed as a "soft" photocatalyst material for hydrogen (H 2 ) production from water under visible light. The CPG offers a hierarchical nanofibrous network structure obtained through self-assembly of a terpyridine alkyl-amide appended porphyrin (TPY-POR)-based low molecular weight gelator with ruthenium ions (Ru II ) and produces H 2 with a rate of 5.7 mmol g −1 h −1 in the presence of triethylamine (TEA) as a sacrificial electron donor. Further, the [Fe 2 (bdt)(CO) 6 ] (dbt = 1,2benzenedithiol) cocatalyst, which can mimic the activity of iron hydrogenase, is coassembled in the CPG and shows remarkable improvement in H 2 evolution (catalytic activity; rate ∼10.6 mmol g −1 h −1 and turnover number ∼1287). The significant enhancement in catalytic activity was supported by several controlled experiments, including femtosecond transient absorption (TA) spectroscopy and also DFT calculation. The TA study supported the cascade electron transfer process from porphyrin core to [Ru(TPY) 2 ] 2+ center, and subsequently, the electron transfers to the cocatalyst [Fe 2 (bdt)(CO) 6 ] for H 2 production.

Aqueous Sol–Gel Synthesis and Shaping of Covalent Organic Frameworks

“…In addition, E ′ displayed a frequency-independent behavior, which was 1 order of magnitude higher than the corresponding loss modulus ( E ″), demonstrating that the elastic characteristic dominated during the application of a load. The values of E ′ were comparable to the widely reported soft materials such as poly­(vinyl alcohol), agarose, and gelatin (0.5–50 kPa) or greater than the reported metal–organic polyhedron-based , and coordination polymer-based colloidal gel network. , …”

“…The values of E′ were comparable to the widely reported soft materials such as poly(vinyl alcohol), 47 agarose, and gelatin 48 (0.5−50 kPa) or greater than the reported metal−organic polyhedron-based 49,50 and coordination polymer-based colloidal gel network. 51,52 Macroscopic Materials Based on the Colloidal Platform and Sol−Gel Process. With the effective method discussed above, we next investigated the processability of the metastable COF colloidal dispersion.…”

Heterogeneous Photocatalysts for Light‐Mediated Reversible Deactivation Radical Polymerization

“…Further, solvent penetration (or the degree of network swelling) can be modified by varying the degree of crosslinking [227] . As such, depending on their design, gels may enhance reaction kinetics through diffusion into the gel resulting favorable microenvironments and increase active catalytic area [228–231] . Photocatalytic polymer gels have been studied for hydrogen production, [228] wastewater treatment, [225,232] dye degradation, [216] and RDRP [224,233] …”

Editorial for Forum on Applied Supramolecular Materials

“…Many important properties and functionalities were realized based on the synergistic role of metal ions and organic components in the field of catalysis, magnetism, and optoelectronics. Verma et al have created a coordination polymer gel (CPG) using porphyrin-based materials that serve as a visible light-driven photocatalyst for hydrogen production from water . The CPG has a hierarchical nanofibrous network structure that results from the self-assembly of a low molecular weight gelator based on terpyridine alkyl-amide appended porphyrin (TPY-POR) with Ru­(II) ions.…”

“…Verma et al have created a coordination polymer gel (CPG) using porphyrin-based materials that serve as a visible light-driven photocatalyst for hydrogen production from water. 7 The CPG has a hierarchical nanofibrous network structure that results from the self-assembly of a low molecular weight gelator based on terpyridine alkyl-amide appended porphyrin (TPY-POR) with Ru(II) ions. In the presence of triethylamine (TEA), the CPG produces H 2 at a rate of 5.7 mmol g −1 h −1 .…”