Self-Assembled Synthesis of Mesocrystalline TiO2@C-rGO Hybrid Nanostructures for Highly Reversible Sodium Storage

With the aim of enhancing the electrochemical kinetics and capacity of the TiO2 electrode for Na ion batteries (NIBs), we have designed a hybrid material of carbon-coated TiO2 mesocrystals anchored on reduced graphene oxide (TiO2@C-rGO). Such hybrid nanostructures are fabricated through a facile one-step route including in situ growth of oriented self-assembly of TiO2 mesocrystals on GO. TiO2@C-rGO possesses a very large surface area (279 m2 g–1), mesoporous nature, and single-crystal-like structure. It is also found that the capacity of TiO2 electrode for NIBs could be improved by carbon coating at a low current rate, but pure TiO2 shows better rate performance than that of TiO2@C. Remarkably, the enhanced electrochemical kinetics and large capacity can be simultaneously achieved by designing hybrid material. The hybrid nanostructures exhibit a highly reversible capacity of 300 mAh g–1 at 100 mA g–1, superior rate capability, and long-term cycling stability (a stable capacity of 159 mAh g–1 can be maintained after 1000 cycles at 1 A g–1). The superior Na ion storage of TiO2@C-rGO is largely ascribed to the robust architecture of well-dispersed carbon-coated mesoporous TiO2 mesocrystals anchored on conductive graphene network, leading to enhanced electrochemical kinetics and offering enough active sites for the Na ion to locate.