Charge controlled capture/release of CH on NbCT MXene: A first-principles calculation.

Methane is not only the main cause of coal mine accidents but also a contributor to global warming, meanwhile, it is clean energy. It is necessary to find an advanced material which can capture methane efficiently for its utilization. In this paper, the adsorption of CH gas molecules on NbCT(T = O, F, Cl, OH) is studied by first-principles calculation. The results indicate that the adsorption of CH on NbCT(T = O, F, Cl, OH) is weak, and the adsorption of CH on NbC(OH) is the best. The calculation results of binding energy and cohesive energy show that NbCO has the best stability. The adsorption behavior of CH on NbCO under charge control is further studied. With the increase of negative charge state in the system, the adsorption of CH on NbCO is significantly enhanced, from physical adsorption to chemical adsorption; when the charge state of the system is greater than or equal to -2, NbCO can capture CH effectively, and the charges transferred from NbCO to CH mainly come from Nb atom. After the removal of the extra charge, the adsorption of CH on NbCO becomes weak and returns to physical adsorption state; CH gas molecules are easy to desorb. Therefore, NbCO can capture and release CH molecules by regulating the charge state of NbCO, and NbCO is expected to become an excellent candidate material for CH capture/release.