Platform Materials for Moisture-Swing Carbon Capture

Energy and cost efficiency limit the viability of direct air carbon capture. Developing and testing materials that can improve these efficiencies and fit into the carbon capture, storage, and utilization ecosystem will be essential to advance negative emissions technologies. This study builds on the moisture-swing modality of carbon capture, directly comparing carbon-based and metal oxide nanomaterials based on their humidity-dependent adsorptive properties. The moisture-swing modality allows for the cyclical sequestration of CO₂ under dry conditions and release under humid conditions. While previous work has explored individual material systems, generally focusing on the use of ion-exchange resins and comparing across different anion types, this work broadens the toolbox of platform materials available, focusing on materials with potential dual-function uses for carbon conversion and storage. Activated carbon, nanostructured graphite, and iron and aluminum oxide nanoparticles showed particular promise, among the studied materials, while manganese oxide, flake graphite, and carbon nanotube powders underperformed. The effects of surface area and pore distributions─the subject of prior theoretical work─were investigated experimentally, yielding insights into establishing design rules for platform materials for moisture-swing carbon capture and other sorbent materials.