By using first principles calculations based on density functional theory (DFT), we studied a mechanism for the efficient capture of multiple CO2 molecules on TMn doped C2N monolayer (TMn = Tin and Scn with n = 1-3). A comprehensive analysis revealed that all the metal clusters bind strongly to C2N monolayer; however the bindings of Scn are stronger than those of Tin clusters. On the basis of electronic structure calculations, it was found that uniformly distributed metal clusters transformed the semiconducting C2N monolayers into metal. The magnetic states of C2N also changed from non-magnetic to magnetic upon the introduction of metal dopants. We found that a maximum of six CO2 molecules could be adsorbed on C2N doped with dimers and trimers of both Sc and Ti clusters. Our van der Waals corrected DFT calculations showed that the average binding energies per CO2 molecule decreased with the increase in the number of incident CO2 molecules to metal functionalized C2N. Overall, Scn doped C2N monolayer anchored the CO2 molecules stronger than that of Tin doping. We believe that these findings would pave the way for the synthesis of efficient CO2 capture medium.