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

Abstract The capture and utilisation of N2 has been limited by the development of high-performance N2 capture and storage materials, and exploring the adsorption mechanism of N2 and searching for new and efficient N2 adsorption materials are the key to solving this technological challenge. In this study, the adsorption properties of d4 and d5 two-dimensional M2N-MXene (M= Sc, Ti, V, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, and Cd) on N2 molecules 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 N2 molecules obtaining a larger adsorption energy on most of the M2Ns than the cis-N2 molecules, and the adsorption of N2 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 Ti2N and Zr2N have a strong binding capacity to N2, and the bond lengths of N2 molecules increase significantly during the adsorption process, implying the weakening of the N-N triple bond, and therefore Ti2N and Zr2N are expected to be the most promising materials for N2 trapping and catalytic reduction, and a simple kinetic thermal stability simulation was done, and it was found that the screened materials may desorb at 500k. Moreover, the adsorption mechanism between N2 and CO2 is not only selective adsorption but also competitive adsorption. The study of N2 adsorption 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.