CO2 selective adsorption over O2 on N−doped activated carbon: Experiment and quantum chemistry study

Utilizing flue gas as feedstock for CO 2 electro−reduction systems is a promising technology to address problems caused by excessive CO 2 emissions. However, the O 2 contained in the flue gas has a significant adverse effect on the CO 2 reduction. Herein, a facile strategy was proposed to suppress the influence of O 2 by constructing a CO 2 −enriched region. N−doping was demonstrated to be an efficient way to enhance CO 2 adsorption selectivity over O 2 on activated carbon. The N−doped activated carbon achieved 3.7 times increase in CO 2 adsorption selectivity over O 2 than that before modification under simulated flue gas atmosphere (75 %N 2  + 15 %CO 2  + 10 %O 2 ). The distinction in adsorption mechanism between CO 2 and O 2 was revealed by quantum chemistry study. The increased polarity of the carbon materials favored CO 2 adsorption and had less impact on O 2 adsorption. The electrostatic interaction between CO 2 and carbon material was demonstrated to be enhanced after the introduction of pyridinic N and pyrrolic N, which led to an improvement in the CO 2 adsorption capacity. The dispersion interaction, which fully regulated O 2 adsorption, was weakened due to the deviation of the O 2 adsorption position. This study provided a reference for the subsequent development of CO 2 selective adsorption materials.