Gram-scale solution-based synthesis of SnSe thermoelectric nanomaterials

Highlights: • Synthesized doped and undoped SnSe nanomaterials at ambient conditions. • The SnSe nanorods having aspect ratios of ~5. • The synthesized SnSe nano-rods used as potential materials for thermoelectric applications. • The pristine SnSe pellets are p-type, and showed slightly higher electrical conductivities compared to those of single crystalline SnSe . • The counterpart n-type SnSe pellets were synthesized by doping Bi and their thermal conductivity was found to be between those of single crystalline SnSe along a- and b-axis (or c-axis) direction. Gram-scale SnSe nanomaterials have been prepared by exploiting a simple wet-chemical route at ambient environments in which a transparent NaHSe solution was mixed with SnCl₂ and sodium ascorbate, followed by hydrothermal heating for 24 h. It is notable that phase-pure crystalline SnSe nanorods having aspect ratios of ∼5 were obtained within a short period of time and without any sophisticated instruments or inert environment. The key steps and conditions to obtain pure SnSe nanorods in the synthesis process were identified and discussed. The SnSe powder was sintered using a facile spark plasma sintering method to form polycrystalline pellets for thermoelectric property measurements. According to the thermopower measurement results, the pristine SnSe pellets are p-type, and showed slightly higher electrical conductivities compared to that of single crystalline SnSe. The counterpart n-type SnSe pellets were also fabricated by doping Bi with a high energy ball milling process. The thermal conductivity of our polycrystalline SnSe was found to be in between that of single crystalline SnSe along a- and b- axis (or c-axis) direction. The facile and new synthesis route, high reproducibility and cost-effectiveness are easily adaptable for the formation of other doped and un-doped metal selenide nanomaterials with a short reaction time for various applications beyond thermoelectrics.