Investigation on photocatalytic property of SiH/GaSe and SiH/InSe heterojunctions for photocatalytic water splitting

The structural stability, electronic structure and optical property of the monolayers SiH, GaSe and InSe as well as constructed SiH/GaSe and SiH/InSe heterojunctions are investigated based on first principles calculations. The band alignment and the charge transfer of SiH/GaSe and SiH/InSe heterojunctions as well as their solar-to-hydrogen production efficiency during photocatalytic process for water splitting are analyzed systematically. The effect of applied electric field or biaxial strain taking on the electronic structure of heterojunctions is also included. The results indicated that the absorption range and intensity of SiH/GaSe and SiH/InSe heterojunctions are significantly improved. Both SiH/GaSe and SiH/InSe heterojunctions have the relatively higher light absorption coefficient in the visible and ultraviolet range. These light absorption capacities are conducive to improve the solar-to-hydrogen production efficiency. Compared with the monolayers SiH, GaSe and InSe, the SiH/GaSe and SiH/InSe heterojunctions have the property of type-II band alignment. This band alignment is also in favor of improving the efficiency of photocatalytic activity. The band gap and band edge structure of SiH/GaSe and SiH/InSe heterojunctions can also be adjusted effectively by applied electric field or biaxial strain, which provides a method for improving the photocatalysis performance.