First-principles computational screening of N₂gas adsorption by two-dimensional M₂N-MXene

The capture and utilization of N₂has been limited by the development of high-performance N₂capture and storage materials, and exploring the adsorption mechanism of N₂and searching for new and efficient N₂adsorption materials are the key to solving this technological challenge. In this study, the adsorption properties ofd⁴andd⁵two-dimensional M₂N-MXene (M = Sc, Ti, V, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, and Cd) on N₂molecules were investigated based on first principles. The results of cohesion energy, energy band structure and partition density indicate that the 15 M₂Ns have excellent stability and electrical properties. In addition, with the lateral N₂molecules obtaining a larger adsorption energy on most of the M₂Ns than the cis-N₂molecules, and the adsorption of N₂depends on its interaction with thed-band electrons of M atoms. The adsorption energies, structural and electronic properties of the adsorption systems indicate that the stable structures of Ti₂N and Zr₂N have a strong binding capacity to N₂, and the bond lengths of N₂molecules increase significantly during the adsorption process, implying the weakening of the N-N triple bond, and therefore Ti₂N and Z_r2N are expected to be the most promising materials for N₂trapping and catalytic reduction, and a simple kinetic thermal stability simulation was done, and it was found that the screened materials may desorb at 500 K. Moreover, the adsorption mechanism between N₂and CO₂is not only selective adsorption but also competitive adsorption. The study of N₂adsorption on M₂N-MXene provides theoretical guidance for the exploration of M₂N in the field of nitrogen capture, storage and catalytic reduction, which can help to promote the economic value-added of nitrogen.