Theoretical study on electronic, optical, magnetic and photocatalytic properties of codoped SrTiO3 for green energy application

Motivated by the large scientific interest in development of double cation doping of SrTiO3 (STO) within the last years aiming to improve the water-splitting activity, electronic and ionic conductivity of STO, we study the effect of (La, X) and (Y, M) codoping (X = Al/Sc/Cr/Mn/Fe/Co/Ni/Mo, and M = Al/Cr/Mo) on the structure, electronic, magnetic, optical and photocatalytic properties (for water-splitting and CO2 reduction) of STO using spin-polarized hybrid density functional theory. In most considered cases, the X and M monodoping reduces the bandgap of STO more than the (La, X) and (Y, M) codoping, except for the case of (La, Ni) codoping. We found out La-/Y-doping, and (La/Y, Al)-/(La, Sc)-codoping cannot improve the conductivity of STO, while other monodopants and codopants can increase it. Our calculations have revealed that the best suited candidates for mono-/co-doped STO-based photocatalysts are Fe-/(La, Ni)-STO. Furthermore, we disclosed Fe-/Mn-/(La, Mn/Fe/Ni)-STO could be appropriate for spintronic applications.