Nb2CO2 as a promising sensor and adsorbent to capture H2CO gas

This paper investigated the potential application of the Nb2CO2-MXene structure as a sensor or adsorbent for formaldehyde (H2CO) in industrial and residential environments. The study utilized the first-principles method based on density functional theory (DFT) to explore the adsorption of formaldehyde on pristine, O-vacancy defected, and transition metals (TMs: Ti, Fe, Co, Ni, Y, and Mo) doped Nb2CO2 structures. The results indicated that the original Nb2CO2 structure weakly adsorbed formaldehyde, with large adsorption distance, small adsorption energy, and low charge transfer. Interestingly, the O-vacancy defect transformed the H2CO adsorption mechanism into chemical adsorption, significantly increasing the adsorption stability. Adding TM-dopants, such as Ti, Fe, and Y, enhanced the interaction between the doped substrates and H2CO, while the effect of Co, Ni, and Mo dopants was insignificant. Further analysis of parameters such as adsorption energy, charge transfer, and magnetism revealed that the Y–VNb2CO2 substrate had good adsorption capacity and stable binding strength with formaldehyde molecules and good stability at room temperature. In addition, the adsorption capacity of Y–VNb2CO2 was explored, and obtained results demonstrated the potential of Y–VNb2CO2 as a formaldehyde gas adsorbent at room temperature. In summary, this study establishes an effective gas adsorbent material for H2CO based on MXenes.