Photo-Responsive Carbon Capture over Metalloporphyrin-C Metal-Organic Frameworks via Charge-Transfer.

Great efforts have been devoted to the study of photo-responsive adsorption, but its current methodology largely depends on the well-defined photochromic units and their photo-driven molecular deformation. Here, a methodology to fabricate nondeforming photo-responsive sorbents is successfully exploited. With C-fullerene doping in metalloporphyrin metal-organic frameworks (PCN-M, M = Fe, Co, or Ni) and intensively interacting with the metalloporphyrin sites, effective charge-transfer can be achieved over the metalloporphyrin-C architectures once excited by the light at 350 to 780 nm. The electron density distribution and the resultant adsorption activity are thus changed by excited states, which are also stable enough to meet the timescale of microscopic adsorption equilibrium. The charge-transfer over Co(II)-porphyrin-C is proved to be more efficient than the Fe(II)- and Ni(II)-porphyrin-C sites, as well as than all the metalloporphyrin sites, so the CO adsorption capacity (CAC; at 0 °C and 1 bar) over the C-doped PCN-Co can be largely improved from 2.05 mmol g in the darkness to 2.69 mmol g with light, increased by 31%, in contrast to photo-irresponsive CAC over all C-undoped PCN-M sorbents and only the photo-loss CAC over C.