Photocatalytic hydrogen production from water offers an abundant, clean fuel source, but it is challenging to produce photocatalysts that use the solar spectrum effectively. Many hydrogen-evolving photocatalysts are active in the ultraviolet range, but ultraviolet light accounts for only 3% of the energy available in the solar spectrum at ground level. Solid-state crystalline photocatalysts have light absorption profiles that are a discrete function of their crystalline phase and that are not always tunable. Here, we prepare a series of amorphous, microporous organic polymers with exquisite synthetic control over the optical gap in the range 1.94-2.95 eV. Specific monomer compositions give polymers that are robust and effective photocatalysts for the evolution of hydrogen from water in the presence of a sacrificial electron donor, without the apparent need for an added metal cocatalyst. Remarkably, unlike other organic systems, the best performing polymer is only photoactive under visible rather than ultraviolet irradiation.

To impact carbon emissions, new materials for carbon capture must be inexpensive, robust, and able to adsorb CO2 specifically from a mixture of other gases. In particular, materials must be tolerant to the water vapor and to the acidic impurities that are present in gas streams produced by using fossil fuels to generate electricity. We show that a porous organic polymer has excellent CO2 capacity and high CO2 selectivity under conditions relevant to precombustion CO2 capture. Unlike polar adsorbents, such as zeolite 13x and the metal-organic framework, HKUST-1, the CO2 adsorption capacity for the hydrophobic polymer is hardly affected by the adsorption of water vapor. The polymer is even stable to boiling in concentrated acid for extended periods, a property that is matched by few microporous adsorbents. The polymer adsorbs CO2 in a different way from rigid materials by physical swelling, much as a sponge adsorbs water. This gives rise to a higher CO2 capacities and much better CO2 selectivity than for other water-tolerant, nonswellable frameworks, such as activated carbon and ZIF-8. The polymer has superior function as a selective gas adsorbent, even though its constituent monomers are very simple organic feedstocks, as would be required for materials preparation on the large industrial scales required for carbon capture.

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The intermolecular interactions between the "polymer of intrinsic microporosity" PIM-1 and polycyclic aromatic hydrocarbons (PAHs) have been investigated with the aim of modifying the gas sorption and physical properties. Mixing PIM-1 with selected PAHs resulted in rapid precipitation of polymer. Blending PIM-1 with pyrene had a significant effect of the gas sorption properties of the resulting films; dramatically reduced N 2 uptake (77 K), whilst CO 2 uptake at 298 K was only slightly reduced. A gateopening behaviour was also observed for the N 2 gas sorption (77 K), which was related to the pyrene content of the blend. Using an electron-donating PAH as the additive resulted in a stronger interaction.By exploiting a post-modification strategy after PIM-1 film formation, the absorption of either pyrene or 1-aminopyrene produced films with higher elastic moduli and greatly improved CO 2 /N 2 gas sorption selectivities (293 K). Single gas permeability measurements revealed that while the 1-aminopyrene modified film possessed reduced CO 2 permeability, it possessed enhanced CO 2 /N 2 selectivity. Importantly, the ageing of the permeability was halted over the 50 days tested, likely due to the physical crosslinking of the polymer chains by 1-aminopyrene. † Electronic supplementary information (ESI) available: The ESI contains further photographs investigating the precipitation of PIM-1 into solutions of pyrene. Dynamic light scattering analysis of PIM-1 precipitation with pyrene, gas sorption data comparing the effect of length of time used for the methanol soaking of PIM-1 lms, a photograph of PIM-1 and PAH blends dried to give lms, UV-Vis data for the relationship between pyrene concentration in solution and the amount of pyrene absorbed by the PIM-1 lm, visual and SEM comparison of post-modied PIM-1 lms, and transmission UV-Vis of PIM-1 lms post-modied with pyrene. See