Conversion of inert N2 molecules into NH3 via electrochemical methods is an environmentally friendly alternative to replace the traditional Haber-Bosch process.However,the development of highly efficient catalyst is still challenging.Herein,we report a density functional theory(DFT)based high-throughput screening to investigate the potential of 23 atomic transition metals(Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn,Y,Zr,Nb,Mo,Tc,Ru,Rh,Pd,Ag,Cd,W,Pt and Au)supported on phosphorene monolayer as electrocatalyst for nitrogen reduction reaction(NRR).Our theoretical results demonstrate that V single atom anchoring on phosphorene monolayer exhibits good thermal stability,selectivity and excellent catalytic activity with a low overpotential of 0.18 V.Importantly,rational design principles and electronic descriptor between the intrinsic electronic properties and activation barrier have been developed.Our work offers a new promising noble metal-free catalyst for NRR and reveals profound insights into the activity origin to guide further design.