LAUSR

Abstract A novel two–step method has been proposed to synthesize Ti 3 C 2 T x @CNTs three–dimensional composites. At the outset, the thin layer of polydopamine (PDA) was coated on Ti 3 C 2 T x and served as protective cover to achieve the structural stability and integrity of Ti 3 C 2 T x . CNTs were then in situ grown on Ti 3 C 2 T x layers via a simple pyrolysis process using urea as carbon source, and the length and density of the grown CNTs can be effectively controlled by altering the amount of urea in the synthesis process. The vertically−aligned CNTs not only provided channels for electrolyte transport, but also greatly expanded the interlayer space of Ti 3 C 2 T x sheets. When applied as electrode materials for supercapacitor energy storage, the Ti 3 C 2 T x @CNTs 6.0 composites revealed a high areal capacity of 924.9 mF cm -2  at 2 mV s -1 and an advantageous retentive capacity of 78.1% at 1 A g -1 after 10,000 cycles.