GFP Chromophore Integrated Conjugated Microporous Polymers toward Bioinspired Photocatalytic CO₂ Reduction to CO

The development of highly active, durable, and low-cost metal-free catalysts for the photocatalytic CO₂ reduction reaction (CO₂RR) is an efficient and environmentally friendly solution to address significant problems like global warming and high energy demand. In the present study, we have demonstrated the design and synthesis of a donor-acceptor based conjugated microporous polymer (CMP), TPA-GFP, by integrating an electron donor, tris(4-ethynylphenyl)amine (TPA), with a green fluorescent protein chromophore analogue (Z)-4-(2-hydroxy-3,5-diiodobenzylidene)-1-(4-iodophenyl)-2-methyl-1H-imidazol-5(4H)-one (o-HBDI-I3) (GFP). In comparison to nondonor 1,3,5-triethynylbenzene (TEB) based TEB-GFP CMP, photocatalytic CO₂ reduction using donor-acceptor based TPA-GFP CMP displays a 3-fold increment of CO production yield with a maximum CO yield of 1666 μmol g^-1 at 12 h. Further, the CO selectivity increases significantly from a mere 54% in TEB-GFP to an impressive 95% in TPA-GFP. The impressive CO₂ reduction efficiency and selectivity for TPA-GFP can be attributed to the efficient light-harvesting capability and facile charge separation and migration through donor-acceptor building units of the CMP. The mechanistic aspect of the photocatalytic CO₂ reduction process is explored using in situ DRIFTS and DFT calculation, and a plausible photocatalytic mechanism is proposed.