ScholarWorks@성균관대학교

초록

The development of multifunctional construction materials capable of both structural support and direct energy harvesting from environmental temperature gradients represents a significant step toward sustainable, self-powered infrastructure. In this study, we present a novel and scalable strategy for fabricating thermoelectric (TE) cement composites by employing an aqueous suspension of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as a multifunctional dispersant for multi-walled carbon nanotubes (MWNT). This hybrid network enables the cement matrix to convert waste heat into electrical energy while maintaining mechanical integrity and thermal stability, thereby allowing structural elements to function simultaneously as energy-harvesting modules. The synergy between the MWNT network and the PEDOT:PSS phase enables simultaneous improvement of electrical conductivity, Seebeck coefficient (S), and mechanical strength while maintaining thermal stability. Varying MWNT content revealed a percolation threshold near 0.5 wt%, producing a 4.3-fold conductivity increase and stable conductive pathways at higher loadings. The S displayed non-monotonic behavior due to the interplay between enhanced carrier transport and increased carrier concentration. Thermal conductivity rose moderately with MWNT addition via phonon transport along interconnected nanotube pathways, but remained low enough to sustain TE efficiency. The optimized composite achieved a power factor of 1.33 × 10⁻⁵ μW/m∙K² and a ZT of 3.53 × 10⁻⁹ at room temperature. At 0.5 wt% MWNT, a peak 28-day compressive strength of 33.1 MPa (19.5 % higher than plain cement) was obtained. These findings highlight the potential of MWNT/PEDOT:PSS-modified cement as a robust platform for integrating structural performance with thermoelectric energy harvesting in infrastructure applications.

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