Transition Metal Doping Effect On Strontium Titanate Electronic Structure And Optical Properties

In the21st century, global environmental problem and energy crisis are twofundamental factors of constraint the sustainable development of human society, forthis reason environmental pollution and development of green energy resource is oneof the most important topic of science and engineering fields. Due to the advantages ofenergy-saving and environmental protection, Semiconductor photocatalyst is widelyapplication in the preparation of clean energy, especially the decomposition of waterto production hydrogen. As an important perovskite oxides，SrTiO3has uniqueoptoelectronic properties and high photocatalytic activity. Unfortunately, SrTiO3catalysts are active only under UV irradiation due to its large band gaps, whichoccupies only about4%of the whole solar spectrum while others absorbing visiblelight are not stable during the reaction process。In recent years, doping a small amountof foreign elements into a semiconductor to change its photocatalytic properties makeit response to the visible light become one of research hotspots in the field. In thispaper, we address the transition metal atoms Rh Pd and Ag doped in the perovskiteoxide SrTiO3with an emphasis on the electronic structures and the photocatalyticabsorption by first-principles. The main achievements are listed as follows:(1) By using first principles method to study Rh doped SrTiO3system, via thecalculation of formation indicate that Pd impurities will replace the Sr atom first; thebad gap will decrease to1.9eV for Rh replace Ti and2.9eV for Rh replace Sr.Therefor doping Rh atom can extension SrTiO3absorption band edge.(2) In the Pd doped SrTiO3system, through the calculation of formation indicatethat Pd impurities will replace the Sr atom first; The bad gap will decrease to2.3eVfor Pd replace Sr. But the photocatalytic activity is reduced for the Pd4d state isformed in the band gap also as optical electronic-hole pair recombination center. Inthe case of Pd replace Sr the band gap decrease to1.8eV. As a consequence doping Pdcan improve the photocatalytic activity of SrTiO3(3) For the calculation of Ag doped SrTiO3system indicate that Ag impuritieswill replace the Sr atom at first. In the case of Ag replace Ti, the band gap change toindirect band gap semiconductor, its direct band gap turn into2.4eV and its indirectband gap is1.3eV. And the band decrease to2.1eV in the case of Ag take the place ofSr. As a result, doping Ag impurities can improve the photocatalytic activity of SrTiO3 In this paper, the calculation results to promote the practical application ofstrontium titanate photocatalytic materials provide a theoretical reference.