Cement-Based Thermoelectric Device for Protection of Carbon Steel in Alkaline Chloride Solution

The thermoelectric cement-based materials can convert heat into electricity; this makes them promising candidates for impressed current cathodic protection of carbon steel. However, attempts to use the thermoelectric cement-based materials for energy conversion usually results in low conversion efficiency, because of the low electrical conductivity and Seebeck coefficient. Herein, we deposited polyaniline on the surface of MnO(2) and fabricated a cement-based thermoelectric device with added PANI/MnO(2) composite for the protection of carbon steel in alkaline chloride solution. The nanorod structure (70~80 nm in diameter) and evenly dispersed conductive PANI provide the PANI/MnO(2) composite with good electrical conductivity (1.9 ± 0.03 S/cm) and Seebeck coefficient (−7.71 × 10(3) ± 50 μV/K) and, thereby, increase the Seebeck coefficient of cement-based materials to −2.02 × 10(3) ± 40 μV/K and the electrical conductivity of cement-based materials to 0.015 ± 0.0003 S/cm. Based on this, the corrosion of the carbon steel was delayed after cathodic protection, which was demonstrated by the electrochemical experiment results, such as the increased resistance of the carbon steel surface from 5.16 × 10(2) Ω·cm(2) to 5.14 × 10(4) Ω·cm(2), increased charge transfer resistance from 11.4 kΩ·cm(2) to 1.98 × 10(6) kΩ·cm(2), and the decreased corrosion current density from 1.67 μA/cm(2) to 0.32 μA/cm(2), underlining the role of anti-corrosion of the PANI/MnO(2) composite in the cathodic protection system.