Chen Zhang

More than 90% of the world’s hydrogen (H ₂ ) is produced from fossil fuel sources, which requires energy-intensive separation and purification to produce high-purity H ₂ fuel and to capture the carbon dioxide (CO ₂ ) by-product. While membranes can decarbonize H ₂ /CO ₂ separation, their moderate H ₂ /CO ₂ selectivity requires secondary H ₂ purification by pressure swing adsorption. Here, we report hyperselective carbon molecular sieve hollow fiber membranes showing H ₂ /CO ₂ selectivity exceeding 7000 under mixture permeation at 150°C, which is almost 30 times higher than the most selective nonmetallic membrane reported in the literature. The membrane is able to maintain an ultrahigh H ₂ /CO ₂ selectivity over 1400 under mixture permeation at 400°C. Pore structure characterization suggests that highly refined ultramicropores are responsible for effectively discriminating the closely sized H ₂ and CO ₂ molecules in the hyperselective carbon molecular sieve membrane. Modeling shows that the unprecedented H ₂ /CO ₂ selectivity will potentially allow one-step enrichment of fuel-grade H ₂ from shifted syngas for decarbonized H ₂ production.

Biogenic-based foam, renowned for its sustainable and eco-friendly properties, is emerging as a promising thermal insulating material with the potential to significantly enhance energy efficiency and sustainability in building applications. However, its relatively high thermal conductivity, large-pore configurations, and energy-intensive manufacturing processes hinder its widespread use. Here, we report on the scalable, one-pot synthesis of biogenic foams achieved by integrating recycled paper pulp and in situ nanoporous silica formation, resulting in a hierarchical structure comprising both micropores and nanopores. Ambient solvent-exchange drying can preserve the pore structure by reducing the capillary forces during the drying process. The resulting flame-retardant and hydrophobic foam exhibits low density (0.110 g/cm³), ideal porosity (70.69%), excellent thermal conductivity (0.033 W/(m·K)), and impressive compressive strength (1.48 MPa at 80% strain). This recyclable biogenic foam, with its hierarchical pore structure and environmental durability, shows great potential for energy-efficient building applications.