Efficiency of volatile organic compound degradation in air using doped strontium titanate photocatalysts. Quenching experiments towards understanding of doping mechanisms

SrTiO3 doped with vanadium, iridium, rhodium and chromium possess absorption bands in the visible light. These bands can be ascribed to the excitation from the discontinuous donor levels formed by the dopant metals to the conduction band of SrTiO3 or from the valence band of SrTiO3 to discontinuous acceptor levels. All materials generate anodic photocurrents under visible light and show good photocatalytic activity towards VOC (volatile organic compound) degradation. By using experiments with various radical scavengers-benzoquinone as a scavenger of superoxide anion radical and isopropanol for scavenging a hydroxyl radical, the band structure is proposed. Briefly, vanadium doping offers additional acceptor levels just below the conduction band edge; chromium, iridium, and rhodium doping offers the additional donor states above the valence band edge. The novelty of paper results from the determination the position of additional doping-levels within the band gap based on radical quenching experiments.