Coverage-Dependent Adsorption Behavior of N‑Containing Gases on Nb₂CT _x MXenes: A DFT Study

The regulation mechanism of surface functional group coverage on Nb-based MXenes for nitrogen-containing gas adsorption is systematically explored via density functional theory calculations. The adsorption behaviors of typical nitrogen-containing gases on Nb₂CT _x MXenes with gradient -F and -O surface coverage are comprehensively characterized. Optimal selective adsorption is revealed to be achieved by partial functional group coverage via balancing active site exposure and electron transfer efficiency, while full coverage is found to significantly weaken gas-surface interfacial interactions. The intrinsic correlation among adsorption energy, adsorption distance, and charge transfer quantity is confirmed, providing critical theoretical guidance for the rational design of high-performance MXene-based gas-sensing and nitrogenous pollutant capture materials.