Scalable Polymeric Few-Nanometer Organosilica Membranes with Hydrothermal Stability for Selective Hydrogen Separation

Nanoporous silica membranes exhibit excellent H₂/CO₂ separation properties for sustainable H₂ production and CO₂ capture but are prepared via complicated thermal processes above 400 °C, which prevent their scalable production at a low cost. Here, we demonstrate the rapid fabrication (within 2 min) of ultrathin silica-like membranes (∼3 nm) via an oxygen plasma treatment of polydimethylsiloxane-based thin-film composite membranes at 20 °C. The resulting organosilica membranes unexpectedly exhibit H₂ permeance of 280-930 GPU (1 GPU = 3.347 × 10^-10 mol m^-2 s^-1 Pa^-1) and H₂/CO₂ selectivity of 93-32 at 200 °C, far surpassing state-of-the-art membranes and Robeson's upper bound for H₂/CO₂ separation. When challenged with a 3 d simulated syngas test containing water vapor at 200 °C and a 340 d stability test, the membrane shows durable separation performance and excellent hydrothermal stability. The robust H₂/CO₂ separation properties coupled with excellent scalability demonstrate the great potential of these organosilica membranes for economic H₂ production with minimal carbon emissions.