• The reaction path of low temperature RWGS on M/C 2 N (M=Cu, Co, Fe) was studied by DFT. • After doping, electrons transfer from m to C 2 N and gather directionally on the surface of C 2 N. • Low-temperature RWGS on Cu/C 2 N and Co/C 2 N proceed to redox mechanism, while Fe/C 2 N tend to carboxyl mechanism. • The energy barrier of rate-determining step in redox mechanism for Cu/C 2 N is the lowest. The reaction path of low temperature reverse water gas reaction (RWGS) on M/C 2 N (M=Cu, Co, Fe) was studied by density functional theory (DFT). The results show that after doping, electrons transfer from M to C 2 N and gather directionally on the surface of C 2 N, which significantly changes the catalytic behavior of C 2 N. Because the increase of electronic activity reduces the reaction activation energy, it effectively promotes the RWGS on C 2 N at low temperature. We also found that the low-temperature RWGS on Cu/C 2 N and Co/C 2 N proceed according to the redox mechanism, while Fe/C 2 N tend to the carboxyl mechanism. Moreover, the energy barrier of rate-determining step in redox mechanism for Cu/C 2 N is the lowest, indicating that the low-temperature RWGS reaction is more likely to occur on this structure. [Display omitted] [ABSTRACT FROM AUTHOR]