TiO₂ Nanopowder Co-Doped with Iodine and Boron to Enhance Visible-Light Photocatalytic Activity

An iodine and boron co-doped TiO₂ photocatalyst was prepared by the hydrolyzation-precipitation method. X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and X-ray photoelectron spectroscopy (XPS) were applied to characterize the crystalline structure, light absorbing ability, and the chemical state of iodine and boron in the photocatalysts. The results of photocatalytic degradation of methyl orange demonstrated that the I-B-TiO₂ catalyst prepared at 400 °C for 3 h exhibited the highest photocatalytic activity with a methyl orange degradation ratio of 61% under visible-light ( ≥ 420 nm) irradiation for 120 min. The characterization results revealed that I-B-TiO₂ is in conformity with the anatase TiO₂ and that the doping of iodine and boron ions could efficiently inhibit the grain growth. Doped iodine was present in the multivalent forms of I⁷⁺, I⁻ and I⁵⁺. Doped boron was present as B³⁺ in an as-prepared sample, forming a possible chemical environment such as B–O–Ti. Overall, the doping of I and B enhanced the ability of TiO₂ to absorb visible-light, and it was observed that the photocatalytic activity of I-B-TiO₂ was enhanced by the synergistic effect of I and B.