Mixed “ionic-electronic” thermoelectric effect of reduced graphene oxide reinforced cement-based composites

Incorporating functional fillers can provide electronic carriers to enhance the electronic thermoelectric effect of cement-based materials. However, the enhancement of the thermoelectric effect by incorporating multiple kinds and high amounts of such functional fillers might increase the cost, degrade the mechanical properties, and thus hinder the wider applications of the thermoelectric cement-based materials. It may be beneficial to develop a new strategy to improve the thermoelectric effect and at the same time to reduce the content of the functional fillers. In this study, the mixed “ionic-electronic” thermoelectric effect is proposed and evaluated for the cement-based composite. The cement pastes at the reduced graphene oxide (rGO) contents of 0.00 wt%, 0.05 wt%, 0.10 wt%, 0.15 wt% were fabricated, of which the thermoelectric effect is measured and analyzed under the conditions of after sealed curing, after drying, and after leaching. It is found that after the leaching process, the cement-based composite incorporated with rGO (rGO/C) becomes a mixed “ionic-electronic” thermoelectric cement-based composite (M-TECC) due to the cooperative work between the metal cations and the holes carriers provided by pore solution and rGO, respectively. The power factor representing the thermoelectric conversion efficiency is significantly improved as well. The findings of this study provide a new perspective for improving the thermoelectric effect of cement-based composites.