P- and n-type thermoelectric cement composites with CVD grown p- and n-doped Carbon nanotubes: Demonstration of a structural thermoelectric generator

•Thermal energy harvesting by cement/CNT composite structural materials.•Synthesis of p- and n-doped CNTs by CVD.•P- and n-doped CNTs convert cement into p- and n-type thermoelectric (TE) material.•Cement/n-CNT with highest conductivity of 1.86 S/m and Seebeck coefficient −880 µV/K.•Demonstration of a structural thermoelectric generator (TEG) with p/n junctions.