High relative permittivity and excellent dye photo-elimination: Pure and (Zr4+, Y3+, Sb5+) multi-doped anatase TiO2 structure

Abstract

Herein, multifunctional characteristics including solar photocatalytic, dielectric constant and ac electrical conductivity have been studied for pure and Zr4+, Y3+ and Sb5+ multidoped TiO2 n-type semiconductor. Pure, Zr doped, (Zr, Y) codoped and (Zr, Y, Sb) tridoped TiO2 with chemical compositions of TiO2, Ti0.98Zr0.02O2, Ti0.96Zr0.02Y0.02O2 and Ti0.94Zr0.02Y0.02Sb0.02O2 were prepared via a low cost coprecipitation technique. All compositions reveal a pure single phase of anatase TiO2 structure with different unit cell volume due to the differences in ionic radii between parent cation (Ti4+ = 0.605 Å) and dopants ions (Zr4+ = 0.72 Å), (Y3+ = 0.9 Å) and (Sb5+ = 0.6 Å). Morphological changes for TiO2 particles were seen due to incorporation of Zr4+, Y3+ or Sb5+ cations into TiO2 lattice. Optically, Zr4+, Y3+ and Sb5+ ions cause a red shift for the absorption edge and reduce the width of the bang gap energy of TiO2 as well as enhance its refractive index value. High dielectric constant of 2214 (42 Hz) was detected for Ti0.94Zr0.02Y0.02Sb0.02O2 composition. Ti0.94Zr0.02Y0.02Sb0.02O2 sample reveals the highest ac electrical conductivity (σac) values compared to undoped TiO2, Ti0.98Zr0.02O2 and Ti0.96Zr0.02Y0.02O2 samples. High efficiency (∼100%) and fast (20–40 min) solar photodegradation characteristics for 10 ppm Congo red (CR) was realized via TiO2 and Ti0.96Zr0.02Y0.02O2 catalysts. For 40 ppm CR, pure TiO2 exhibits a high photocatalytic activity of 80% after 120 min of sunlight irradiation. Interestingly, this study also illustrates that the starting materials (titanium butoxide-butanol solvent) used in the synthesis process play a significant role in the phase structure as well as the ultimate photocatalytic properties of TiO2 based compositions.