Ex Situ Method for Photoreduction of the Cadmium Ion from Terbium-Loaded Bismuth Vanadium Oxide

Abstract

The photoreduction of Cd (II) to Cd (0) was performed using Bi₄V₂O₁₁, which was tremendously enhanced by Tb³⁺-doped Bi₄V₂O₁₁. The relationship between charge carrier isolation and light harvesting was studied in depth in this research, and a promising technique for fabricating effective photocatalysts for heavy metals was discovered. Lattice disorder effects due to size variance between V⁵⁺ and Tb³⁺ cations in Bi₄V₂O₁₁ nanomaterials substituted with an invariable Tb³⁺ cation at different concentrations (<i>x</i> = 15, 20, and 25%). Bi₄V₂O₁₁ and 15% Tb/Bi₄V₂O₁₁ evidenced a coexistence of monoclinic (α-phase) with a <i>CS/m</i> symmetry, while 25% Tb/Bi₄V₂O₁₁ was tetragonal (γ-phase) with an <i>I</i>4/<i>mmm</i> symmetry. Raman scattering experiments elucidated the changes in Bi₄V₂O₁₁ lattice corresponding to oxygen motion, suggesting significant destabilization of the VO₄ tetrahedra after addition of Tb³⁺. The SEM micrograph depicted a disparity in the microstructure with reduced grain size in 25% Tb/Bi₄V₂O₁₁ samples. However, the TEM micrographs of 25% Tb/Bi₄V₂O₁₁ nanomaterials revealed that crystallite sizes of 25-35 nm were obtained, presenting a single tetragonal phase, highly homogeneous in nature. Impedance spectroscopy was used to study the conductivity of these compounds in the temperature range of 300 °C. At 300 °C, the compounds with <i>x</i> = 25% showed a conductivity of 15.92 S cm^-1. The conductivity values were found to be comparable with the highest values reported in the literature for similar compounds.