Controlled Nanostructuring via Aluminum Doping in CuO Nanosheets for Enhanced Thermoelectric Performance

Abstract Copper oxide (CuO) nanosheets (NS) produced by the microwave chemical assisted route were reported to have attractive structural and thermoelectric (TE) properties. They possess the non-agglomeration property and have two-dimensional (2D) ultra-thin NS with a high Seebeck coefficient and relatively elevated electrical conductivity. This study controlled nanostructuring of CuO NS via aluminum (Al) doping has been investigated for its effect on this material's structural and TE performance. Various concentrations of aluminum (Al) in the range 0.5-5 mol% were incorporated in the host of CuO NS. Increasing the concentration of this dopant was observed to systematically reduce the size of the NS with no effect on their crystallinity. Moreover, the Seebeck coefficient of the Al-doped CuO NS was increased, while the electrical conductivity kept almost invariant. In sharp contracts, the thermal conductivity was significantly decreased, which results in an enhanced TE figure of merit, zT. The zT value was increased from around 0.004 for the pure CuO NS to approximately 0.09 for the 5 mol % Al-doped sample at room temperature. This broad difference was reduced by heating to 673 K, where the zT values for pure and 5 mol % Al-doped CuO NS recorded 0.2 and 0.9, respectively. The TE generated powers of designed modules from pure CuO NS and Al-doped CuO NS (5 mol %) were measured. The TE generated power from the Al-doped CuO NS (5 mol %) was 7 μW at 673 K, which is 5 times higher than that of the pure CuO NS sample. These results showed that the Al-doped CuO NS could be a promising TE nanomaterial.