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

The structural, electronic, optical, and photocatalytic properties of 2D Y 2 CF 2 and Lu 2 CF 2 MXenes are investigated by density functional theory approach. According to the obtained results, 2D Y 2 CF 2 and Lu 2 CF 2 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 Y 2 CF 2 (Lu 2 CF 2). 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, Y 2 CF 2 and Lu 2 CF 2 MXenes can be used for O 2 /H 2 O 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-C 3 N 4 , a Z-scheme Y 2 CF 2 or Lu 2 CF 2 /g-C 3 N 4 heterojunction can be considered to increase the CO 2 photocatalytic reaction under solar light irradiation. All obtained results exhibit that M 2 CF 2 (M=Y, Lu) monolayers are promising candidates for optoelectronic, solar energy and photocatalytic applications. • The strain effects on structural, electronic, optical and photocatalytic properties of 2D Y 2 CF 2 and Lu 2 CF 2 MXenes are investigated. • The transition from indirect to direct bandgap occurred in the tensile strain of 8% (12%) for 2D Y 2 CF 2 (Lu 2 CF 2). • Y 2 CF 2 and Lu 2 CF 2 have potential application as photocatalyst for O 2 /H 2 O water splitting half-reaction. • The Z-scheme Y 2 CF 2 or Lu 2 CF 2 /g-C 3 N 4 heterojunction can be a proper candidate to increase the CO 2 photocatalytic reaction. [ABSTRACT FROM AUTHOR]