First-principles computational screening of N2 gas adsorption by two-dimensional M2N-MXene

Abstract The capture and utilization of N 2 has been limited by the development of high-performance N 2 capture and storage materials, and exploring the adsorption mechanism of N 2 and searching for new and efficient N 2 adsorption materials are the key to solving this technological challenge. In this study, the adsorption properties of d 4 and d 5 two-dimensional M 2 N-MXene (M = Sc, Ti, V, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, and Cd) on N 2 molecules were investigated based on first principles. The results of cohesion energy, energy band structure and partition density indicate that the 15 M 2 Ns have excellent stability and electrical properties. In addition, with the lateral N 2 molecules obtaining a larger adsorption energy on most of the M 2 Ns than the cis-N 2 molecules, and the adsorption of N 2 depends on its interaction with the d -band electrons of M atoms. The adsorption energies, structural and electronic properties of the adsorption systems indicate that the stable structures of Ti 2 N and Zr 2 N have a strong binding capacity to N 2 , and the bond lengths of N 2 molecules increase significantly during the adsorption process, implying the weakening of the N–N triple bond, and therefore Ti 2 N and Z r2 N are expected to be the most promising materials for N 2 trapping 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 N 2 and CO 2 is not only selective adsorption but also competitive adsorption. The study of N 2 adsorption on M 2 N-MXene provides theoretical guidance for the exploration of M 2 N in the field of nitrogen capture, storage and catalytic reduction, which can help to promote the economic value-added of nitrogen.