Two-Dimensional Layered Ultrathin Carbon/TiO₂ Nanosheet Composites for Superior Pseudocapacitive Lithium Storage

Abstract

Intercalation of carbon nanosheets into two-dimensional (2D) inorganic materials could enhance their properties in terms of mechanics and electrochemistry, but sandwiching these two kinds of materials in an alternating sequence is a great challenge in synthesis. Herein, we report a novel strategy to construct TiO₂ nanosheets into 2D pillar-layer architectures by employing benzidine molecular assembly as pillars. Then, 2D carbon/TiO₂ nanosheet composite with a periodic interlayer distance of 1.1 nm was obtained following a polymerization and carbonization process. This method not only alleviates the strain arising from the torsion of binding during carbonization but also hinders the structural collapse of TiO₂ due to the intercalation of the carbon layer by rational control of annealing conditions. The composite material possesses a large carbon/TiO₂ interface, providing abundant active sites for ultrafast pseudocapacitive charge storage, thus displaying a superior high-rate performance with a specific capacity of 67.8 mAh g^-1 at a current density of 12.8 A g^-1 based on the total electrode and excellent cyclability with 87.4% capacity retention after 3000 cycles.