Abstract
The limited flux and selectivities of current carbon dioxide membranes and the high costs associated with conventional absorption-based CO(2) sequestration call for alternative CO(2) separation approaches. Here we describe an enzymatically active, ultra-thin, biomimetic membrane enabling CO(2) capture and separation under ambient pressure and temperature conditions. The membrane comprises a ~18-nm-thick close-packed array of 8 nm diameter hydrophilic pores that stabilize water by capillary condensation and precisely accommodate the metalloenzyme carbonic anhydrase (CA). CA catalyzes the rapid interconversion of CO(2) and water into carbonic acid. By minimizing diffusional constraints, stabilizing and concentrating CA within the nanopore array to a concentration 10× greater than achievable in solution, our enzymatic liquid membrane separates CO(2) at room temperature and atmospheric pressure at a rate of 2600 GPU with CO(2)/N(2) and CO(2)/H(2) selectivities as high as 788 and 1500, respectively, the highest combined flux and selectivity yet reported for ambient condition operation.