Structural, electronic, optical, thermoelectric and photocatalytic properties of SiS/MXenes van der Waals heterostructures

Abstract

Vertical stacking of two-dimensional materials into layered van der Waals heterostructures are recently considered as promising candidates for optoelectronic devices because they can combine advantages of the individual 2D materials. MXenes have emerged an appealing optoelectronic material due to the desirable electronic properties. This paper focuses on the structural, electronic, optical, thermoelectric and photocatalytic properties of SiS, Ti2CO2, Zr2CO2, Hf2CO2 monolayers and their corresponding van der Waals (vdW) heterostructures. These materials and their heterostructures are dynamically stable. All unstrained heterostructures show indirect band gap semiconductors except SiS-Ti2CO2 which exhibits metallic nature. The higher carrier mobility of the metallic, SiS-Ti2CO2 is followed by its least effective mass. The induction of considerable biaxial (compressive and tensile) strain offers metallic characteristics to SiS-Ti2CO2 and SiS-Zr2CO2 while SiS-Hf2CO2 retains its semiconducting nature. SiS-Zr2CO2/SiS- Hf2CO2 show type-I/type-II band alignment which are highly suitable for electronic, optical, nanoelectronic and optoelectronic devices. Additionally, the least effective mass of SiS-Zr2CO2 offers higher carrier mobility. Bader charge analysis revealed that MXenes dissipate the charge carriers to SiS monolayer. Furthermore, a good comparison of thermoelectric performance of all the systems illustrates their significant power factor that is well interpreted at 300 K and 800 K. Several excitonic peaks are observed of the systems in the visible region of solar spectrum. Furthermore, valence (conduction) band edge potentials are calculated to understand the photocatalytic behavior of these systems.