Theoretical study on structural properties and hydrogen adsorption performance of C3N doped with monoatomic Al/Li

Abstract

In this paper, density functional theory (DFT) was used to study the structural properties, charge transfer, thermodynamic stability and hydrogen storage properties of C3N two-dimensional materials and atomic defects C3N doped with Al and Li (Al/VN-C3N, Al/VC-C3N, Li/VN-C3N and Li/VC-C3N), respectively. The results show that Al/Li doping does not reduce the stability of C3N structure, and C3N, Al/VN-C3N, Al/VC-C3N and Li/VN-C3N have good thermal stability at room temperature (300 K). The calculation results of H2 adsorption show that Li/VN-C3N has the best adsorption performance, and the average adsorption energy of single H2 is −0.289 eV. When adsorbing multiple hydrogen molecules, the energy of the four doped C3N materials first increased from 0.2 eV to 0.5 eV and then decreased to 0.4 eV on average. The decrease is small, indicating that it was possible to adsorb more hydrogen. When adsorbing six hydrogen molecules, the absolute value of the adsorption energy reaches the maximum. Thus, four doped C3N materials, particular for Li/VN-C3N, have the potential to become new hydrogen storage materials.