Abstract
Abstract Sintered carbon nanotube (CNT) blocks and porous CNT sponges were prepared, and their thermoelectric properties were measured. The maximum dimensionless thermoelectric figure-of-merit, ZT, at room temperature of the sintered single-walled carbon nanotube (SWCNT) block is 9.34 × 10−5, which is twice higher than that of the sintered multi-walled carbon nanotube (MWCNT) block in this work and also higher than that of other sintered MWCNT blocks reported previously. In addition, the porous MWCNT sponge showed an ultra-low thermal conductivity of 0.021 W/(m K) and significantly enhanced ZT value of 5.72 × 10−4 at room temperature and 1 atm. This ZT value is higher than that of other 3D macroscopic pure CNT materials reported. The pronounced enhancement of the ZT in the porous MWCNT sponge is attributed to the ultra-low density, ultra-high porosity, and interconnected structure of the material, which lead to a fairly low thermal conductivity and better Seebeck coefficient. The finding of this work provides an understanding for exploring potential enhancement mechanisms and improving the thermoelectric properties of CNT-based thermoelectric composites.
Highlights
Sintered carbon nanotube (CNT) blocks and porous carbon nanotubes (CNTs) sponges were prepared, and their thermoelectric properties were measured
The objective of our work is to provide a clear understanding of the thermal conductivity and thermoelectric properties for pure CNT bulk materials via our comprehensive experimental research
The microscopic morphology of the CNT macroscopic material was characterized by scanning electron microscopy (Zeiss, Merlin compact)
Summary
Abstract: Sintered carbon nanotube (CNT) blocks and porous CNT sponges were prepared, and their thermoelectric properties were measured. The porous MWCNT sponge showed an ultra-low thermal conductivity of 0.021 W/(m K) and significantly enhanced ZT value of 5.72 × 10−4 at room temperature and 1 atm. This ZT value is higher than that of other 3D macroscopic pure CNT materials reported. The thermoelectric properties of the bulk material were measured in the directions perpendicular and parallel to the pressure direction Both the thermal conductivity and electrical conductivity show apparent anisotropy, but the thermoelectric power has close values in the two different directions and the ZT of SWCNT bulk reached 4.3 × 10−5 at room temperature. This study could provide help in exploring potential enhancement mechanisms and improving the thermoelectric properties of CNT-based thermoelectric composites
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