In a recent study, a modified spray deposition technique for the fabrication of CNT films over large areas was developed. The process is inherently low cost and flexible as it operates at atmospheric pressure and temperature, using aqueous precursors and can produce 150 nm–5 µm thick CNT meso-porous films at 0.1–5 m2/h through a single nozzle. A suspension of CNTs was delivered to a spray nozzle via a hypodermic needle by a syringe pump, where the suspension was atomized into thousands of droplets using compressed air at up to 200 kPa. The fine mist deposited on a heated substrate, which drove off the liquid carrier (usually water) to form a continuous CNT film. The film thickness was easily controlled by adjusting the flow rate of the suspension and relative speed between the nozzle and substrate.

The spray deposition technique has been applied for the fabrication of CNT electrodes for supercapacitors. The spray-deposited CNT electrodes showed good capacitive behaviour, cycling performance and mechanical durability. Furthermore, the possibility of using various covalent functionalized single-walled and multi-walled CNTs has been investigated and the performance of the resulting electrodes has been shown to be a strong function of CNT surface chemistry. The authors are currently studying the performance of CNT electrodes in different electrolytes and developing strategies for the manufacture and application of CNT films at the near-industrial scale.

The group published its results in Nanotechnology.