Enhanced CO Adsorption by Modulating the Electron Density Distribution of Graphite-Copper Porphyrin Sorbents with Light

The photo-responsive adsorption has emerged as a vibrant area, but its current methodology is limited by the well-defined photochromic units and their molecular deformation driven by photo-stimuli. Herein, a methodology of nondeforming photo-responsiveness is successfully exploited. With the exploiting agent of Cu-TCPP framework assembled on the graphite and strongly interacted with it, the sorbent generates two kinds of adsorption sites, over which the electron density distribution of the graphite layer can be modulated at the c-axis direction, which can further evolve due to photo-stimulated excited states. The excited states are stable enough to meet the timescale of microscopic adsorption equilibrium. Independent of the ultra-low specific surface area of the sorbent (20 m² g⁻¹), the CO adsorption capability can be improved from 0.50 mmol g⁻¹ at the ground state to 1.24 mmol g⁻¹ (0 °C, 1 bar) with the visible light radiation, rather than the photothermal desorption.