Y2CF2 and Lu2CF2 MXenes under applied strain: Electronic, optical, and photocatalytic properties

Abstract

The structural, electronic, optical, and photocatalytic properties of 2D Y2CF2 and Lu2CF2 MXenes are investigated by density functional theory approach. According to the obtained results, 2D Y2CF2 and Lu2CF2 are indirect bandgap semiconductors of ~1.67 eV and ~1.42 eV, respectively. The indirect-to-direct bandgap transition was observed at the tensile strain of 8% (12%) for Y2CF2 (Lu2CF2). It is worth noting that the dynamical stability of these structures was confirmed. The optical properties including complex dielectric function, absorption, reflectivity and energy loss function of these MXenes are also studied in both unstrained and strained states. The obtained results reveal the good absorption of these monolayers in the visible and ultraviolet ranges. Furthermore, based on the photocatalytic properties, Y2CF2 and Lu2CF2 MXenes can be used for O2/H2O water splitting half-reaction, keeping this behavior under applied strain. Additionally, according to the band alignments of these materials with respect to that of g-C3N4, a Z-scheme Y2CF2 or Lu2CF2/g-C3N4 heterojunction can be considered to increase the CO2 photocatalytic reaction under solar light irradiation. All obtained results exhibit that M2CF2 (M=Y, Lu) monolayers are promising candidates for optoelectronic, solar energy and photocatalytic applications.