The first-principles calculations of photocatalytic water splitting and photoelectric properties of two-dimensional MoxW1-xS2 and MoS2xSe2(1-x) alloys

The realization of ternary alloys by atomic substitution of two-dimensional (2D) transition metal dichalcogenides (TMDs) is an effective solution to modulate the optoelectronic properties of 2D materials. The MoxW1-xS2 and MoS2xSe2(1-x) (0 ≤ x ≤ 1) alloys with high stability are established and their electronic, optical and photocatalytic performances are systematically investigated based on the first-principles calculations. Our results indicate that the MoxW1-xS2 and MoS2xSe2(1-x) alloys remain direct bandgaps and optical adsorption has excellent ability to capture ultraviolet and visible light. Suitable bandgap at HSE06 level (>1.23 eV) and band edges satisfy the conditions of photocatalytic water splitting under acidic or neutral solutions. Biaxial strain can enhance the alloys direct bandgap ranges. The introductions of W and S in MoS2 and MoSe2 monolayers cause their intrinsic electronic properties to change. The bandgap values, effective masses and work functions as well as optical adsorption properties of the MoxW1-xS2 and MoS2xSe2(1-x) show different behaviors due to the d-d, p-p and d-p orbitals hybridization between Mo, W, S and Se atoms. The absorption coefficients of Mo0·5W0·5S2 and MoS1·5Se0.5 are significantly higher theirs pure binary TMDs. The work provides a valuable theoretical guidance of TMDs alloys application in 2D flexible photoelectric devices and photocatalytic water splitting.