Effect of sulfur doping on the electronic structures, optical and photocatalytic properties of KTaO3 perovskites: DFT calculations

Perovskite oxides such as KTaO₃ have attracted a great deal of scientific interest in recent years thanks to their remarkable properties, which enable them to be used in a variety of fields. In our case, we've focused on photovoltaic and photocatalytic applications, and it's well-known that these techniques are based on the use of semiconductors with a specific gap value, which indicates that the gap value is an important element that influences the efficiency of panels. The objective of this study is to decrease the gap value by applying the KTaO_3-xS_x doping process with different percentages of S (x = 0 %, 4.16 %, 8.32 %, and 12.5 %) to determine the electronic, optical, and photocatalytic properties of the different percentages of S using density functional theory (DFT). As a result, we reduced the gap value from 3.86 eV to 1.24 eV corresponding to 0 % S and 12.5 % S respectively, and the bandgap changed from an indirect bandgap equivalent to 0 % S to a direct bandgap for 4 %, 8 % and 12 % S.

Conduction and valence band edges were also determined in relation to the oxidation and reduction potentials of water. These results indicate that S-doped KTO_3-xS_x (x = 4.16 % to 8.32 %) are potential candidates for hydrogen production. However, under pH conditions, only KTO_3-xS_x compounds (x = 0 % and 4.16 %) can be used for hydrogen production by photocatalysis of water using solar radiation.