| Abstract |
| We report the effect of interface control using multiwalled carbon nanotubes (MWCNT) on thermoelectric properties of TiO2. By consolidating TiO2 nanoparticles with MWCNT (0.5, 1, 2, 4, and 8 wt%) using spark plasma sintering, we prepared interface-controlled TiO2-MWCNT nanocomposites, where TiO2 grains were surrounded with a MWCNT network. Simultaneous control of charge and thermal transport was successfully achieved by interface control using MWCNTs. The electrical conductivity increased monotonically as the MWCNT content was increased. As determined in our previous report, the charge transport mechanism in the nanocomposites is based on percolation and hopping models. The formation of new interfaces at the grain boundaries using the MWCNT network led to additional phonon scattering in the nanocomposites, and the thermal conductivities decreased monotonically with increasing MWCNT content. However, the incorporation of the MWCNT did not lead to a significant increase in power factor due to a reduction in the Seebeck coefficient. Consequently, the highest ZT value of 4.6 × 10-3 was obtained from the TiO2-0.5 wt% MWCNT nanocomposite at 1073 K. Our results introduce a strategy for the independent control of electron and phonon transport based on interface control using carbon nanomaterials in hybrid thermoelectric materials.
(Received May 8, 2018; Accepted May 23, 2018) |
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| Key Words |
| thermoelectric, TiO2, carbon nanotube, interface control |
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