Boosting power factor of thermoelectric cementitious composites by a unique CNT pretreatment process with low carbon content

Abstract

Thermoelectric cement refers to a cement-based composite material that realizes the mutual conversion of heat energy and electric energy by adding carbon or metal materials and other additives. It has broad application prospects in energy harvesting, low-energy-consumption snow melting and deicing, and mitigation of urban heat island effects. Although the thermoelectric properties of carbon-reinforced cement matrix composites have been studied with great progress, the high carbon material content and low Seebeck coefficient in carbon material reinforced cement matrix composites have become the main bottleneck to improve the thermoelectric properties of carbon material cement matrix composites. In this paper, a methodology is proposed to improve the thermoelectric properties of cementitious composites by pretreating CNT with mixed acid or HCl gas to improve the surface defects. The CNTs were pretreated to induce higher carrier scattering at their interface with the cementitious material, which reduced the carrier mobility and increased the effective carrier mass, thus improving the Seebeck coefficient of cementitious composites. Meanwhile, the power factor and ZT values of cementitious composites were both improved by 300% compared to the untreated ones. This study will inspire us how to improve the thermoelectric properties of cementitious composites at low carbon content.