Research progress in CO2 and NOx adsorption by two-dimensional materials

In order to cope with the sharp rise in carbon dioxide (CO₂) concentrations caused by global industrialization, adsorption of CO₂ is considered a significant way to remove it from flue gas. There is also a large amount of nitrogen oxide (NO_x) emissions in the flue gas containing CO₂. Among various types of adsorbents, two-dimensional (2D) materials were noticed in the field of CO₂ and NO_x adsorption because of their large specific surface area and special structural properties. Two-dimensional materials including graphenes, layered double hydroxides (LDHs), boron nitride (BN), carbon nitride (C₃N₄) and MoS₂ are commonly used for CO₂ and NO_x adsorption. In this review, we introduce the basic structures and properties of these 2D materials and summarize the modification schemes that can improve their CO₂ and NO_x capture ability and stability according to their surface structural characteristics, including functional group grafting, heteroatom doping, and metal modification. Moreover, the reasons for performance optimization are discussed so as to show our understanding of the mechanism of CO₂ and NO_x adsorption by 2D materials. It also provides a reference for the development of 2D materials.