Direct air capture (DAC) technology is a promising carbon removal method with greatpotential to address CO emissions and support the achievement of future carbon neutrality. The highselectivity, low energy consumption, and flexibility of solid amine adsorbents make them ideal for DACapplications. The CO capture capacity of solid amine adsorbents depends on the number of aminegroups present on their surface. Primary and secondary amines typically require two amine groups toform a zwitterion, which enables CO capture via proton transfer. The capture efficiency of both typesof amines is improved under humid conditions due to the assistance of water molecules. Tertiary aminesare usually not used as sources of amines for solid amine adsorbents. This is due to their inability totransfer protons and their low CO capture efficiency. Solid amine adsorbents are often classified intofour types based on their preparation methods: impregnated amine adsorbents, grafted amineadsorbents, in situ polymerization adsorbents, and composite amine adsorbents. Impregnated amineadsorbents involve directly loading amine groups onto a support material. This method is simple,Energy Environmental Protectionresulting in a high amine loading, and typically yielding a high CO capture capacity. However, theweak binding between the amine groups and the support material leads to easy leaching of aminemolecule during recycling, resulting in poor material stability. Grafted amine adsorbents utilize silanolgroups on mesoporous SiO (such as MCM-41, SBA-15) to undergo a silanization reaction (graftingreaction) with amino silane reagents, or cross-coupling to attach amine groups. Chemical bondingprevents amine leaching, thereby improving material stability, which is a limitation of impregnatedadsorbents. However, grafted amines are typically loaded in a single layer on the support, resulting in alower loading capacity compared to impregnation and a relatively lower CO capture capacity. In situpolymerization involves fixing polymeric amine groups to the support material via covalent bonds. Insitu polymerization can further increase the amine load, improve performance, and ensure materialstability. Composite amine adsorbents are prepared by combining impregnation and grafting to improvethe adsorption properties of the materials. Overall, improving the adsorption performance of materialsand reducing preparation costs are the two key challenges for widespread applications. To achieve this,combining solid amine adsorbents with green energy, carbon dioxide resource utilization, and othersystems could improve the commercial viability of the technology and facilitate its large-scaleapplication. The development of highly efficient adsorbents and modular capture devices will be theprimary focus of future research in this field.