Superior Selective CO Adsorption and Separation over N and CH of Porous Carbon Nitride Nanosheets: Insights from GCMC and DFT Simulations.

Development of high-performance materials for the capture and separation of CO from the gas mixture is significant to alleviate carbon emission and mitigate the greenhouse effect. In this work, a novel structure of CN slit was developed to explore its CO adsorption capacity and selectivity using Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) calculations. Among varying slit widths, CN with the slit width of 0.7 nm exhibited remarkable CO uptake with superior CO/N and CO/CH selectivity. At 1 bar and 298 K, a maximum CO adsorption capacity can be obtained as high as 7.06 mmol/g, and the selectivity of CO/N and CO/CH was 41.43 and 18.67, respectively. In the presence of HO, the CO uptake of CN slit decreased slightly as the water content increased, showing better water tolerance. Furthermore, the underlying mechanism of highly selective CO adsorption and separation on the CN surface was revealed. The closer the adsorption distance, the stronger the interaction energy between the gas molecule and the CN surface. The strong interaction between the CN nanosheet and the CO molecule contributes to its impressive CO uptake and selectivity performance, suggesting that the CN slit could be a promising candidate for CO capture and separation.