Enhancing Lithium and Sodium Storage Properties of TiO(B) Nanobelts by Doping with Nickel and Zinc.

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