Synthesis of Mesoporous Co²⁺-Doped TiO₂ Nanodisks Derived from Metal Organic Frameworks with Improved Sodium Storage...

TiO₂ is a most promising anode candidate for rechargeable Na-ion batteries (NIBs) because of its appropriate working voltage, low cost, and superior structural stability during chage/discharge process. Nevertheless, it suffers from intrinsically low electrical conductivity. Herein, we report an in situ synthesis of Co²⁺-doped TiO₂ through the thermal treatment of metal organic frameworks precursors of MIL-125(Ti)-Co as a superior anode material for NIBs. The Co²⁺-doped TiO₂ possesses uniform nanodisk morphology, a large surface area and mesoporous structure with narrow pore distribution. The reversible capacity, Coulombic efficiency (CE) and rate capability can be improved by Co²⁺ doping in mesoporous TiO₂ anode. Co²⁺-doped mesoporous TiO₂ nanodisks exhibited a high reversible capacity of 232 mAhg^-1 at 0.1 Ag^1-, good rate capability and cycling stability with a stable capacity of about 140 mAhg^-1 at 0.5 Ag^1- after 500 cycles. The enhanced Na-ion storage performance could be due to the increased electrical conductivity revealed by Kelvin probe force microscopy measurements.