DFT-Based Study of CO2 Adsorption Mechanism on Carbon Materials

Carbon-based material adsorption is one of the research hotspots in the Carbon Capture, Utilization, and Storage (CCUS) field, and its surface functional groups have a significant impact on CO2 adsorption performance. This study uses Density Functional Theory (DFT) methods to explore the adsorption mechanism of CO2 on the surface of carbon-based materials by examining changes in parameters such as adsorption energy before and after the reaction process. It also studies the influence of different functional groups on the surface of carbon-based materials on CO2 adsorption performance. Research shows that under different doping conditions, the adsorption energy of CO2 on carbon-based materials can be roughly divided into three levels: when both C=C and C=O double bonds are formed, the adsorption energy reaches the highest level; the structure with the C–N single bond accompanied by the C=O double bond reduces the adsorption energy by one level; and when only C=C double bonds exist, the adsorption energy is at the lowest level. Meanwhile, the incorporation of functional groups such as N, NH+ and O2 will reduce the adsorption energy of carbon-based materials for CO2 to varying degrees. Notably, N and NH+ modification not only introduces new nitrogen active sites but also optimizes material performance while maintaining a relatively high adsorption capacity, thus demonstrating good modification potential.