Electronic properties, quantum capacitance and photocatalyst for water splitting of Sc₂CO₂ MXene under uniaxial strain

MXenes have wide applications because of the structural flexibility and compositional diversity. Quantum capacitance, electronic and photocatalytic properties of Sc2CO2 monolayer under uniaxial strains are investigated by first-principles calculation. Sc2CO2 monolayer can withstand stress up to 13.96 N/M and about 14% tensile uniaxial strain limit. Sc2CO2 undergoes a transition from semiconductor to metal at -15% uniaxial strain. Sc2CO2 under uniaxial strains are only used for the water reduction at pH = 0. Sc2CO2 under uniaxial strains of -10%, -7%, -3%, 0%, and 4% within the appropriate pH scope are potential photocatalysts for water redox reaction. Sc2CO2 with -15% uniaxial strain is promising anode material, and Sc2CO2 with tensile uniaxial strain is more potential cathode material. Wide voltage improves the top quantum capacitance at negative bias under uniaxial strain and keeps the type of electrode materials. Quantum capacitance of Sc2C with mixed termination (Sc2CO0.59F1.19(OH)(0.22)) under uniaxial strain is explored. The introduction of uniaxial strain and mixed termination has little effect on the electrode type of Sc2CO2 MXene.