Two?dimensional transition metal carbides and nitrides (MXenes) have become a high?profile material with a wide range of application prospects due to their efficient adsorption and catalytic properties,wide optical absorption range,and excellent conductivity.Ni?doped Nb₂C material has positive photocatalytic properties.To explore the intrinsic mechanism of photocatalytic property improvement by Ni?doped Nb₂C,the electronic structure properties of Nb₂C and its Ni?functionalized form(i.e.,Ni?Nb₂C) and their adsorption properties for CO₂ gas molecule by using the density functional theory (DFT) were investigated.The results show that the replacement of an Nb atom by a Ni atom makes the charge density around the Ni atom increase and further results in a redistribution of the charge density of the substrate,which leads to an improved electronic environment for catalyzing CO₂ and improves the photocatalytic property for CO₂.