Prediction of nodal-line semimetals in 2D ScX (X = P, As) with high stability and considerable fermi velocities

•New nodal–line ternary semimetals of ScX (X = P, As) are proposed.•Fully optimized structures still keep good structural integrity at high temperature of 1000 K.•The SOC effect and physical biaxial strain are negligible for the nodal-line of ScX.•The considerable Fermi velocities which are the same order of magnitude as graphene.•The elastic constants and transport properties of ScX (X = P, As) show nice anisotropy. The nodal–line structure provides higher carrier mobility, massless and special features in which the conduction band and the valence band cross at the Fermi level. The anisotropic nodal–line structure has the advantage of anisotropic Fermi velocity for novel 2D quantum device. Here we report two binary monolayers with anisotropic nodal–line based on first-principles calculation. Fully optimized ScX (X = P, As) structure can still keep good structural integrity at high temperature of 1000 K in ab initio molecular dynamics simulation. Besides, we analyze structural symmetry and wave function to illustrate the existence of nodal–line, the Young’s modulus and Poisson’s ratio of ScX show nice anisotropy. The Fermi velocities of ScX are larger than 105 m/s, which are the same order of magnitude as graphene. This work provides novel candidates of nodal–line semimetals for massless and stable quantum devices.