Probing the Electronic Properties, Charge Polarization, and Quantum Capacitance of Novel Janus ScMCO2 (M = Ti, V, Cr, Mn, Fe, Y, Zr, Nb, Mo, Lu, Hf, Ta, W) MXenes as Supercapacitor Electrodes

Janus two-dimensional (2D) materials have superior properties for their broken symmetry. Herein, the electronic properties, charge polarization, quantum capacitance of Janus ScMCO2 (M = Ti, V, Cr, Mn, Fe, Y, Zr, Nb, Mo, Lu, Hf, Ta, W) MXenes are studied by density functional theory (DFT). The broken symmetry in Janus systems induces the appearance of internal electric field (Ein). The Ein in Janus ScMCO2 (M = Ti, Cr, Y, Lu) MXenes are all larger than 0.10 eV/Å, and the positive Ein for all systems indicates that the direction of Ein is from ScO to MO layers. ScZrCO2 and ScHfCO2 are indirect magnetic semiconductors with the magnetic moments (MMs) of 1.0 μB. ScCrCO2, ScMnCO2, and ScFeCO2 have strong magnetism with MMs of 3.0, 3.60, and 2.32 μB, which are mainly from M atoms. ScMCO2 (M = Mn, Ti, V) are anode materials. Other systems are considered as cathode materials in aqueous system.