Abstract
In this work, a series of two-dimensional (2D) large-size nanosheets were prepared through one-step exfoliation of the huge K&sub4;Nb₆O17 crystals. The K&sub4;Nb₆O17 nanosheets with the thickness of about 2 nm was used as the templates of dopamine polymerization and was then carbonized to form C-doped K&sub4;Nb₆O17 nanosheets. More importantly, the C-doped K&sub4;Nb₆O17 nanosheets exhibited excellent electrochemical performance with high specific capacity (381 mA h g-1 at 0.05 A g-1, 0.5⁻3.0 V vs. Li/Li⁺) and stable cyclability at high current density (remarkably, preserved a capacity of discharge approximately 90 mA h g-1 at 5 A g-1 after 1000 cycles). The good electrochemical performances of the C-doped K&sub4;Nb₆O17 nanosheets can be attributed to the outstanding 2D structure and large specific surface, which afforded the short transport route for ion and electron. These noteworthy results demonstrated that the new 2D nanomaterials might be potential candidates for the high-performance, environmentally friendly, and low-cost electrochemical energy storage equipment.