Regulating the electronic properties, quantum capacitance and photocatalytic activity of Sc2CO2 based on Y doping and strain

Abstract

The doping of transition metals can effectively modulate the electronic structures and enhance the photocatalytic activity of MXenes. The electronic and photocatalytic properties, as well as the quantum capacitance of Sc₂CO₂-Y under biaxial strain, were studied by density functional theory. Sc₂CO₂-Y is a direct semiconductor and keeps its semiconductor character under strain. Sc₂CO₂-Y under tensile strain has higher photocatalytic activity than under compressive strain. In particular, Sc₂CO₂-Y at 2% strain has the slowest recombination rate of electrons and holes because of the largest . Sc₂CO₂-Y under strain is a potential cathode material. Its large potential keeps the character of cathode materials for Sc₂CO₂-Y under strain. Sc₂CO₂-Y under tensile strain has better conductivity, especially under 5% strain, due to having the largest Re (ε₀). Sc₂CO₂-Y under strain can perform the HER, but fails to perform the OER at pH = 0, and tensile strain increases the reduction capacity of Sc₂CO₂-Y. Under strains from −2% to 2%, Sc₂CO₂-Y can perform the OER in an alkaline environment. Sc₂CO₂-Y is a good CO₂ photocatalyst in acidic environments; the increase of pH value weakens the N₂ reducing capacity of Sc₂CO₂-Y under strain. Its work function, charge transfer and optical properties are also explored.