Solvothermal synthesis and growth mechanism of ultrathin Sb2Te3 hexagonal nanoplates with thermoelectric transport properties

Uniform single-crystalline hexagonal-shaped Sb2Te3 nanoplates with a thickness of 30-40 nm have been successfully synthesized by a glucose-assisted solvothermal process in the mixed solvents of ethanediamine and water. It is found that the reaction time, concentration of glucose, reaction temperature and the volume ratio of ethanediamine to water play important roles in the formation of the uniform Sb2Te3 nanoplates. Based on the experimental results, the possible reaction process and formation mechanism of these hexagonal nanoplates is proposed. Different from previous reports, the growth process of such Sb2Te3 nanoplates can be reasonably explained by a self-assembly process and an Ostwald ripening mechanism. The thermoelectric transport properties are investigated by measuring the electrical conductivity and the Seebeck coefficient in the temperature range of 300-600 K. The samples show much more enhanced Seebeck coefficients than that of bulk Sb2Te3. Meanwhile, the size of the sample has much impact on both the electrical conductivity and the Seebeck coefficient.