Enhanced thermoelectric properties of cement-based composites by Cl2/HNO3 pretreatment of graphene

Cement-based composites with thermoelectric effect have important application prospects in alleviating urban heat island effect, low-energy snow and ice melting on winter roads, and low-cost scale energy conversion and harvesting. Great progress has been made in the study of the thermoelectric properties of cement-based composites enhanced with carbon materials, and the addition of carbon materials increases the electrical conductivity of cement-based composites, but easily decreases the Seebeck coefficient. Reduced graphene oxide (RGO) by Cl-2/HNO3 pretreatment increased the electrical conductivity of cement-based composites while also improving the Seebeck coefficient of cement-based composites, which was attributed to the increased content of RGO defects, which increased the effective mass of carriers, thus enhancing the Seebeck effect of cement-based composites and improving the thermoelectric properties of cement-based composites. When the Cl-2 pretreatment RGO content was 5.0wt%, the electrical conductivity of the cement-based composites was 1.54 S/cm, the Seebeck coefficient was -56.61 mu V/degrees C and the ZT(max) value of 1.08 x 10(-4) was achieved, with average output power and thermoelectric conversion efficiency of 2.91 x 10(-2) mW/m(2) and 3.79 x 10(-6). The cement-based composites prepared by Cl-2 pretreatment of RGO achieved the highest ZT at the same carbon material content.