DFT-Based Study for the Enhancement of CO Adsorption on Metal-Doped Nitrogen-Enriched Polytriazines.

Nitrogen-enriched polytriazine (NPT), a carbon nitride-based material, has received much attention for CO storage applications. However, to enhance the CO uptake capacity more efficiently, it is necessary to understand the interaction mechanism between CO molecules and NPT through appropriate modification of the structures. Here, we introduce a method to enhance the CO adsorption capacity of NPT by incorporating metal atoms such as Sn, Co, and Ni into the polytriazine network. DFT calculations were used to investigate the CO adsorption mechanism of the polytriazine frameworks by tracking the interactions between CO and the various interaction sites of NPT. By optimizing the geometry of the pure and metal-containing NPT frameworks, we calculated the binding energy of metal atoms in the NPT framework, the adsorption energy of CO molecules, and the charge transfer between CO molecules and the corresponding adsorption systems. In this work, we demonstrate that the CO adsorption capacity of NPT can be greatly enhanced by doping transition-metal atoms into the cavities of NPT.