Vertical two-dimensional WS2 flakes grown on flexible CNT film for excellent electrochemical performance

Soft electrochemical actuators that can generate mechanical motions in response to electrical stimuli can be used as artificial muscles in microscale robots. The electrode materials are the key component of the electrochemical actuator because they limit the ion diffusion and accumulation processes and thus affect the deformation in fast response-time and potential engineering applications. Low-dimensional materials, such as one-dimensional (1D) CNT and two-dimensional (2D) vertically stood WS2, are great electrode due to their good electrochemical stability and high surface-to-volume ratios, but show limited performances when being used on their own in the actuators because of low reconstruction or low conductivity. A combination of 1D CNT and 2D WS2 could form a heterojunction with both high electrochemical activity and great mechanical stability. Herein, by depositing highly disordered graphene nanosheets (HDGNs) on CNT films and then WS2 on the formed low-dimensional nanocarbon film, a hybrid WS2/HDGN/CNT film was synthesized through a multistep CVD method. Vertically grown WS2 nanosheets were achieved by taking advantage of HDGNs which limits CNTs sliding. So, the volume expansion caused by the transition from WO3 to WS2 can force the vertical growth of WS2. This hybrid film shows excellent electrochemical properties, such as high specific capacitance and high rate performance. Soft actuators based on the WS2/HDGN/CNT films show good actuating performance, including stability and reconfigurability.