Exploring the potential of multifunctional MWCNT/PDMS nanocomposites in thermal and mechanical energy harvesting

Abstract

In this work, it was shown that a nanocomposite of multi-walled carbon nanotubes (MWCNTs) and polydimethylsiloxane (PDMS) is a versatile material that can convert both thermal and mechanical energy into electrical energy. The MWCNT/PDMS nanocomposite with a MWCNT concertation of 2 mass% was chemically etched to expose the carbon nanotubes on the surface of the nanocomposite. This resulted in a significant reduction in contact resistance, an increase in electrical conductivity, and consequently, an improvement in thermoelectric properties. For the first time, the MWCNT/PDMS nanocomposite was thoroughly analyzed to characterize its thermoelectric and triboelectric properties. Electrical conductivity, specific heat, thermal diffusivity, and thermal conductivity were investigated as a function of temperature in a wide range from 298 to 373 K. The optimized characteristics of the MWCNT/PDMS nanocomposite were achieved due to its relatively high electrical conductivity (22 S cm(-1)) and low thermal conductivity (0.22 W m(-1) K-1). The Seebeck coefficient and thermoelectric efficiency factor were found to increase with temperature, reaching the maximum values of 4.6 mu V K-1 and 7.4 & centerdot;10(-5), respectively. The MWCNT/PDMS nanocomposite was used as a negative friction layer in a triboelectric nanogenerator (TENG). This device operated in contact-disconection mode, generating an output voltage of 7 V and a current of 113 nA. During long-term testing, the TENG demonstrated exceptional stability and repeatability of its voltage response. It was shown that the MWCNT/PDMS-based TENG is suitable for harvesting mechanical energy from human body movements, such as finger tapping, foot tapping, and hammering. The developed MWCNT/PDMS nanocomposite shows great potential for use in flexible wearable sensors for self-powered temperature monitoring and motion detection.