Superior Selective CO<sub>2</sub> Adsorption and Separation over N<sub>2</sub> and CH<sub>4</sub> of Porous Carbon Nitride Nanosheets: Insights from GCMC and DFT Simulations
Zilong Liu, Xue Li, Di Shi, Fengzhi Guo, Ge Zhao, Yanxiao Hei, Yufei Xiao, Xiao Zhang, Yun Peng, Weichao Sun
Abstract
Development of high-performance materials for the capture and separation of CO 2 from the gas mixture is significant to alleviate carbon emission and mitigate the greenhouse effect. In this work, a novel structure of C 9 N 7 slit was developed to explore its CO 2 adsorption capacity and selectivity using Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) calculations. Among varying slit widths, C 9 N 7 with the slit width of 0.7 nm exhibited remarkable CO 2 uptake with superior CO 2 /N 2 and CO 2 /CH 4 selectivity. At 1 bar and 298 K, a maximum CO 2 adsorption capacity can be obtained as high as 7.06 mmol/g, and the selectivity of CO 2 /N 2 and CO 2 /CH 4 was 41.43 and 18.67, respectively. In the presence of H 2 O, the CO 2 uptake of C 9 N 7 slit decreased slightly as the water content increased, showing better water tolerance. Furthermore, the underlying mechanism of highly selective CO 2 adsorption and separation on the C 9 N 7 surface was revealed. The closer the adsorption distance, the stronger the interaction energy between the gas molecule and the C 9 N 7 surface. The strong interaction between the C 9 N 7 nanosheet and the CO 2 molecule contributes to its impressive CO 2 uptake and selectivity performance, suggesting that the C 9 N 7 slit could be a promising candidate for CO 2 capture and separation.