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

Abstract

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 Cl₂/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 Cl₂ 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 μV/°C and the ZT_max value of 1.08 × 10⁻⁴ was achieved, with average output power and thermoelectric conversion efficiency of 2.91 × 10⁻² mW/m² and 3.79 × 10⁻⁶. The cement-based composites prepared by Cl₂ pretreatment of RGO achieved the highest ZT at the same carbon material content.

Keywords:

• Reduced graphene oxide
• cement-based composites
• defect engineering
• thermoelectric properties

Disclosure statement

The authors declare no competing financial interest.

Funding

This study was supported by the National Natural Science Foundation of China General Project (51578448), National Natural Science Youth Fund Project (51308447), Shaanxi Province Outstanding Youth Science Foundation (2021JC-43), Shaanxi Province Natural Science Basic Research Program-Major Basic Research Project (2017ZDJC-18), Scientific Research Program Funded by Shaanxi Provincial Education Department (Grant/Award Number: 20JY042) and Technology Foundation for Selected Overseas Chinese Scholar, Ministry of Human Resources and Social Security of the People’s Republic of China (Shan Ren She Han [2016]789).