Nickel- and zinc-doped TiO₂(B) nanobelts were synthesized using a hydrothermal technique. It was found that the incorporation of 5 at.% Ni into bronze TiO₂ expanded the unit cell by 4%. Furthermore, Ni dopant induced the 3d energy levels within TiO₂(B) band structure and oxygen defects, narrowing the band gap from 3.28 eV (undoped) to 2.70 eV. Oppositely, Zn entered restrictedly into TiO₂(B), but nonetheless, improves its electronic properties (E_g is narrowed to 3.21 eV). The conductivity of nickel- (2.24 × 10⁻⁸ S·cm⁻¹) and zinc-containing (3.29 × 10⁻⁹ S·cm⁻¹) TiO₂(B) exceeds that of unmodified TiO₂(B) (1.05 × 10⁻¹⁰ S·cm⁻¹). When tested for electrochemical storage, nickel-doped mesoporous TiO₂(B) nanobelts exhibited improved electrochemical performance. For lithium batteries, a reversible capacity of 173 mAh·g⁻¹ was reached after 100 cycles at the current load of 50 mA·g⁻¹, whereas, for unmodified and Zn-doped samples, around 140 and 151 mAh·g⁻¹ was obtained. Moreover, Ni doping enhanced the rate capability of TiO₂(B) nanobelts (104 mAh·g⁻¹ at a current density of 1.8 A·g⁻¹). In terms of sodium storage, nickel-doped TiO₂(B) nanobelts exhibited improved cycling with a stabilized reversible capacity of 97 mAh·g⁻¹ over 50 cycles at the current load of 35 mA·g⁻¹.

The article describes the synthesis of composite sorbents by immobilizing iron oxide in a polymer matrix with subsequent hydrothermal treatment at a temperature of 175 °C. The sorbents based on magnetite and hematite were synthesized, their magnetic properties and phase composition were evaluated, and the iron content was determined. Sorption characteristics of the composites towards microconcentrations of Sr-90 radionuclide in solutions with different mineralization and pH were investigated. It was shown that the sorbent based on magnetite was the most efficient. In alkaline media with pH above 11, the composite sorbent based on magnetite exhibited increased selectivity towards Sr-90 and proved to be suitable for application under dynamic sorption conditions with subsequent desorption of the radionuclide with a solution of HNO₃.

Introduction of magnetic nanoparticles into composite sorbents based on polymer matrices has received great attention due to the possibility of using cheap iron oxides and removing spent sorbents by means of magnetic separation. In the present paper, we discuss the problem of creating magnetic sorbents using two types of matrices as host materials: synthetic cation exchange resin and natural aminopolysaccharide chitosan. The possibilities of applying matrices for the in situ formation of oxide phases of a specified composition with the required content of an inorganic component in a composite material were estimated. The composition of the oxide phase formed in the composite material was studied, and particle sizes were evaluated by the method of X-ray diffraction analysis. Magnetic characteristics were investigated. Sorption characteristics with respect to strontium for the composites containing iron oxides were determined.

The gray-colored oxygen-deficient TiO_2–δ(B) nanobelts have been synthesized through a combination of the hydrothermal method followed by an ion exchange process and vacuum annealing. Electron paramagnetic resonance reveals an existence of F-centers in the form of electron-trapped oxygen vacancies within the anionic sublattice of the gray bronze TiO₂ that induces its colouration. The diffuse reflectance spectroscopy showed that the formation of oxygen vacancies into TiO₂(B) significantly increases its absorption intensity in both visible and near infrared ranges. The band gap of TiO₂(B) with anionic defects is equal to 3.03 eV (against 3.24 eV for white TiO₂(B) treated in air). Room temperature ferromagnetism associated with the defects was detected in gray TiO_2–δ(B), thus indicating it belongs it to the class of dilute magnetic oxide semiconductors. It was found that in the low-temperature range (4 K), the magnetic properties of vacuum annealed TiO₂(B) do not differ from those for TiO₂(B) treated in air. We hope that the findings are defined here make a contribution to further progress in fabrication and manufacturing of defective TiO₂-based nanomaterials for catalysis, magnetic applications, batteries, etc.