Nanoarchitectonics of Metal-Free Porous Polyketone as Photocatalytic Assemblies for Artificial Photosynthesis.

The main component of natural gas is methane, whose combustion contributes to global warming. As such, sustainable, energy-efficient, nonfossil-based methane production is needed to satisfy current energy demands and chemical feedstocks. In this article, we have constructed a metal-free porous polyketone () with donor-acceptor (D-A) groups with an extensive π-conjugation by facile Friedel-Crafts acylation reaction between triphenylamine () and pyridine-2,6-dicarbonyl dichloride (). is a metal-free catalyst for visible-light-driven CO photoreduction to CH, which can be used as a solar fuel in the absence of any cocatalyst and sacrificial agent. CH production (152.65 ppm g) is ∼5 times greater than that of g-CN under the same test conditions. Charge-density difference plots from excited-state time-dependent density functional theory (TD-DFT) calculations indicate a depletion and accumulation of charge density among the donor/acceptor functional groups upon photoexcitation. Most notably, binding energies from DFT demonstrate that HO is more strongly bound with the pyridinic nitrogen group than CO which shed insight into mechanistic pathways for photocatalytic CO reduction.