Development of sorbent materials for direct air capture of CO₂

Building a carbon–neutral world requires the removal of excess CO ₂ that has already been dumped into the atmosphere. The technologies have been well established to remove carbon dioxide directly from ambient air, or “direct air capture” (DAC). DAC is still in its infancy, with many challenges remaining. Sorbents are central to the capture of CO ₂ from ambient air. Many sorbents have been reported to take up CO ₂, but they all have advantages and disadvantages. Recent advances in material synthesis and surface chemistry have resulted in new generations of CO ₂ sorbents. Development needs to progress quickly, because global warming will not wait. We summarize recent progress on designed sorbents for CO ₂ capture from ambient air. There are mainly six typical technologies for DAC, including physical sorption, sorption by strong bases, sorption by amine-modified materials, sorption by aqueous amino acid solution followed by precipitation with a guanidine compound, moisture-swing sorption, and electrochemical-swing sorption. Existing research works have put forward future perspectives and directions of sorbent materials for DAC technologies. Graphical abstract: [Figure not available: see fulltext.]