Insight the CO2 adsorption onto biomass-pyrolysis derived char via experimental analysis coupled with DFT calculation.

• Mechanism of CO2 adsorption on biomass derived carbon was explained using DFT methods. • Building the relationship between nucleophilicity and adsorption capacity of biochar. • Carboxyl and diketone groups are the most active O-containing sites. • TG-MS experiments proved the effect of nucleophilicity group of biochar on CO 2 adsorption. CO 2 adsorption is an important issue for sustainable development today. In this study, zigzag edge and armchair edge cluster models containing oxygen-containing groups were established, and the interaction with CO 2 molecules was calculated based on Density functional theory. The results indicated that the carboxyl and diketone groups have the CO2 adsorption capacity. The relationship between CO 2 adsorption performance and nucleophilicity of O-containing groups was established. A subsequent TG-MS experiment also proved that the introduction of nucleophilic group can promote interaction between CO 2 and carbon surface. [ABSTRACT FROM AUTHOR]