Investigation on AgGaSe2 for water splitting from first-principles calculations.

The electronic structure of AgGaSe₂ has been investigated as a photocatalyst candidate by first-principles calculation. Our results demonstrate that the band edge positions of bulk AgGaSe₂ straddle the water redox potentials. From the band offset calculation, we find that Al-doping of AgGaSe₂ shifts the conduction band minimum upwards, whereas Cu-doping of AgGaSe₂ shifts the valence band maximum upwards. By (Ag, Cu)(Ga, Al)Se₂ alloying one can thereby tailor both the band edge positions and the band gap energy, and this effect provides an approach to optimize the band properties for overall water splitting. Moreover, AgGaSe₂ forms a suitable junction with CuGaSe₂ with a type-II band offset, which facilitates electron-hole separation. The AgGaSe₂ and CuGaSe₂ junction can be designed as a tandem photoelectrochemical device to improve the photocatalytic properties of the system. [ABSTRACT FROM AUTHOR]