Polydopamine-Modified Metal-Organic Framework Membrane with Enhanced Selectivity for Carbon Capture.

In this work, a versatile postmodification strategy based polydopamine (PDA) grafting is reported for improving CO2 separation performance of MOF membranes. Owning to the strong bioadhesion, PDA can be deposited on the UiO-66 membrane through a simple and mild process. Since PDA impregnation in invalid nanometer-sized pinholes and grain boundaries of the MOF membrane suppress nonselective gas transports, the modified PDA/UiO-66 membrane exhibits significantly enhanced CO2/N2 and CO2/CH4 selectivities of 51.6 and 28.9, respectively, which are 2-3 times higher than the reported MOF membranes with similar permeance. Meanwhile, because PDA modification do not change UiO-66 intrinsic pores and membrane thickness is submicrometer-sized, the CO2 permeance is 2-3 orders of magnitude larger than those membranes with similar selectivity, up to 3.7 × 10-7 mol m-2 s-1 Pa-1 (1115 GPU). Moreover, the PDA/UiO-66 membrane with good reproducibility has excellent long-term stability for CO2 capture under moist condition in 36 h measurement period.