First-principles prediction of enhanced photocatalytic activity in La-X (X = Sc, V, Cr, Mn, Fe, Co, Ni, or Cu) Co-doped SrTiO3

Abstract

The influence of La-X (X = Sc, V, Cr, Mn, Fe, Co, Ni, or Cu) co-doping on the electronic structure and photocatalytic activity of SrTiO3 system was investigated using the open-source software package Quantum Espresso (QE) based on density functional theory. Defect formation energy calculations showed an energy advantage for co-doped systems under Ti-poor and O-rich conditions. The La-V, La-Cr, La-Mn, La-Fe, and La-Ni co-doped systems showed magnetic properties with corresponding total magnetization of 0.08 µB, 2.97 µB, 3.30 µB, 1.00 µB and 1.00 µB, respectively. The La-X (X = V, Cr, Mn, Fe, Ni, or Cu) co-doped system exhibits photoabsorption activity in the visible region as compared to the pure SrTiO3. The La-X (X = Cr, Fe, Ni, or Cu) co-doped SrTiO3 exhibits a long carrier lifetime, especially the La-Fe co-doped system with a high effective mass ratio of holes to electrons of 5.79. However, the redox potential of the water decomposition reaction of the La-Cu co-doped system is too large, making it unsuitable for water splitting. In summary, the La-X (X = Cr, Fe, or Ni) co-doped systems exhibited intermediate states in the band structure and density of states, which better meet the specific requirements for photocatalysis compared to systems without intermediate states, showing superior photocatalytic potential. The band edge alignment of the three co-doped systems with water redox potentials demonstrated good matching. These findings suggest that La-X (X = Cr, Fe, or Ni) co-doped SrTiO3 is a promising candidate material for solar-driven water splitting.