First-principles study on the adsorption and lithium storage capacities of Hf3C2 and Hf3C2T2(T = O, F, S) MXenes

[Display omitted] •Electronic and lithium storage properties ofHf3C2T2(T = bare, O, F, S) were studied.•The surface functional groups have a significant effect on the valence band.•The theoretical lithium storage capacities of Hf3C2T2(T = bare, O, S) were predicted.•Hf3C2O2 on the CCP site is the most suitable for Li adsorption compared to Hf3C2S2. Based on the theoretical framework of the first principle, the adsorption and theoretical lithium storage capacities of Hf3C2 and surface functionalized Hf3C2T2(T = O, F, S) MXenes were studied. The structural stability of the system and the influence of electrical properties on energy storage properties are analyzed when different functional groups are located in different positions. The formation energy results suggest that the three functional Hf3C2T2(T = O, F, S) structures are energetically stable, and the CCP site is the most stable among the possible sites of HCP, TOP and CCP. By calculating the energy bands and density of states, it is proved that F-functionalized Hf3C2F2 is not conducive to adsorption. During the adsorption process, the lithium intercalation process is carried out in the way of surface adsorption of atoms, in which the HCP site of bare Hf3C2 and the CCP site of functionalized Hf3C2T2 are the most favorable adsorption sites. The storage capacities of bare Hf3C2, Hf3C2O2, and Hf3C2S2 are 287.51 mAhg−1, 271.95 mAhg−1 and 258.00 mAhg−1, respectively. The Hf3C2O2 has a higher lithium storage capacity than Hf3C2S2, so both oxygen functionalized Hf3C2O2 and bare Hf3C2 are promising battery materials.