Title : Biomimetic approach towards visible light-driven hydrogen generation based on a porphyrin-based coordination polymer gel
There has been a widespread interest in developing self-assembled 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 (H2) production from water under visible light. The CPG offers hierarchical nanofibrous network structure obtained through self-assembly of terpyridine alkyl-amide appended porphyrin (TPY-POR) based low molecular weight gelator with ruthenium ions (RuII) and produces H2 with a rate of 5.7 mmol g-1 h-1 in the presence of triethylamine (TEA) as a sacrificial electron donor. Further, [Fe2(bdt)(CO)6] (dbt = 1,2-benzenedithiol) co-catalyst, which can mimic the activity of iron hydrogenase, is co-assembled in the CPG and shows remarkable improvement in H2 evolution (catalytic activity; rate ~10.6 mmol g-1h-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 co-catalyst [Fe2(bdt)(CO)6] for H2 production.
Audience Takeaway Notes:
- The audience will be able to understand how Gel-based soft processable material (i.e., Coordination Polymer Gel) can be utilized for photocatalytic application.
- A novel approach for the development of photocatalyst material with earth-abundant metal ions. This approach can be further extended by designing new gelators molecules. The efficiency of CPG based material towards practical application is more promising compared to traditional solid-state catalysts in many aspects however it is still underexplored.
- The main advantages of using gel-based material for photocatalysis will be explained in detail during this talk, such as, the 3D interconnect network morphology in hydrated self-assembly that enhances the diffusion of reactant towards the catalytic centers during the photocatalytic process.