Enhanced Thermoelectric Efficiency in Mn Doped SnO2 Nanoparticles for Sustainable Waste Heat Recovery

In this study, we investigate the impact of varying manganese (Mn) doping concentrations (1% and 2%) on the structural, optical, and thermoelectric properties of tin dioxide (SnO2) nanoparticles synthesized via a chemical co-precipitation route. Structural analysis using X-ray diffraction (XRD) confirms that SnO2 retains its typical rutile crystal structure. Introducing Mn into SnO2 leads to detectable shifts in the XRD patterns and results in an increase in the crystallite size of the doped nanoparticles. Additionally, the absorption properties of SnO2 nanoparticles are improved with the doping of Mn, resulting in the absorption edge being shifted toward longer wavelengths (redshift). At 900 K, the Mn-doped sample exhibits an electrical conductivity of 108 S/cm, a Seebeck coefficient of 178 µV/K, and a PF of 1.1 × 10–4 W/mK2, which represent significant improvements compared to the undoped material, thereby enhancing the overall thermoelectric performance. All this demonstrates great promise for the application of the Mn-doped SnO2 nanoparticles in numerous thermoelectric applications.