A facile synthesis of hierarchical Cu₂NiSnS₄ nanostructures with low thermal conductivity for thermoelectric applications

In recent decades, quaternary chalcogenides have shown enhanced thermoelectric performance due to their low thermal conductivity. In the present work, we report the thermoelectric properties of flower like Cu₂NiSnS₄ sample prepared at different growth periods by solvothermal method. The structural, morphological, thermal and thermoelectric properties of Cu₂NiSnS₄ have been investigated. The XRD analysis confirms the formation of Cu₂NiSnS₄. HR-SEM analysis reveals that the growth period effectively changes the spherical morphology into hierarchical structures. The prepared Cu₂NiSnS₄ sample at 48 ​h show low electrical resistivity of 1.14 ​× ​10⁻³ ​Ω ​m and high Seebeck coefficient of 179.43 ​μVK⁻¹. The 48-h grown sample with hierarchical structures exhibit low thermal conductivity of 0.3454 ​W ​m⁻¹K⁻¹ ​at 478 ​K compared to other samples. Therefore, sample grown for 48 ​h shows the high-power factor of 27.84μWm⁻¹K⁻² and high figure of merit of (zT) 0.038 ​at 478 ​K compared with others samples. Cu₂NiSnS₄ prepared for 48 ​h indicates promising thermoelectric applications, bestowing to the results of the experiments.