Band Engineering of SrTiO3: Effect of Synthetic Technique and Site Occupancy of Doped Rhodium

Abstract

It is well known that doping of Rh into the SrTiO<inf>3</inf> lattice introduces 4d donor levels within the band gap, which causes reduction in the gap and extends the photocatalytic activity to the visible region of the solar spectrum. The mid-gap states formed also act as recombination centers and diminish the efficiency of the material. Herein, we present a combined theoretical and experimental approach to avoid the formation of the so-called acceptor mid-gap states. For the first time, we study the effect of occupancy of Rh in the Sr site. First-principles calculations reveal that mixed occupancies of Rh into Sr and Ti sites lead to the introduction of acceptor levels within the band gap, leading to decrease in photocatalytic efficiency. A facile one-pot solvothermal approach by avoiding high-temperature calcinations is reported to obtain Rh-doped SrTiO<inf>3</inf> nanoparticles in Rh3+ states, suppressing the formation of Rh4+ states by directing Rh toward Sr sites. The photocatalytic activity of Rh-doped SrTiO<inf>3</inf> nanoparticles is studied in the case of degradation of methylene blue, wherein the 1.0 Rh sample was found to be highly efficient. © 2018 American Chemical Society.