Low lattice thermal conductivity and enhanced thermoelectric performance of SnTe via chemical electroless plating of Ag

Interface engineering has been regarded as an effective strategy to manipulate the thermoelectric performance of materials. Here, we use a facile chemical electroless plating and a spark plasma sintering process to fabricate Ag-plated SnTe bulk. After sintering, a small amount of plated Ag can be doped into SnTe to suppress the Sn vacancies and the others form Ag precipitates with a size distribution from nanoscale to microscale, which introduces Ag/SnTe interfaces to enhance the Seebeck coefficient via energy filtering effect. Simultaneously, these structures result in strong scattering to reach a low lattice thermal conductivity of ~ 0.62 W·m–1·K–1. Consequently, a maximum figure of merit (zT) of ~ 0.67 at 823 K is achieved in 2 wt% Ag-plated SnTe, which is ~ 60% higher than that of pristine SnTe. Moreover, the microhardness indentation test results show that the mean microhardness of 2 wt% Ag-plated SnTe is HV 64.26, which is much higher than that of pristine SnTe, indicating that Ag electroless plating can improve the mechanical properties of SnTe. This work has provided a facile and eco-friendly method to realize the interface engineering for manipulating the thermoelectric and mechanical properties of SnTe.