Proceedings of Materials for Sustainable Development Conference (MAT-SUS) (NFM22)
Publication date: 11th July 2022
Mixed ionic and electronic conductors (MIECs) have been explored for long, due to their favourable properties for energy storage application.[1, 2] However, many technological relevant mixed ionic and electronic conductors contain toxic, heavily regulated (Pb) or relatively scare elements (Li) with high manufacturing cost.[3] Here, we report a low temperature, shape and size tunable (50 – 90 nm) colloidal hot injection approach using widely available precursors for producing sodium-antimony chalcogenide nanocrystals based on earth abundant and non-toxic elements. Three synthetic parameters, reaction temperature/, cationic precursor/, and added ligands are explored as a handles to control the size and shape of NaSbS2 NCs with the impact on nucleation and/or growth of NCs. By systematically varying the reaction temperature, we synthesized NCs with cube, quasi spherical cube and cuboctahedra shaped NCs with different sizes (50 to 90 nm). Systematic study of the added ligand reveals the cooperative role of acid and amine functionality for synthesizing pure phase NaSbS2 NCs. Varying the chain length of the ligand, ranging from 18 carbons to 4 carbons, have shown independent correlation to the size and shape of NCs. Surface chemistry reveals carboxylate and related ligands are passivated to the surface of ternary nanocrystal. Control studies indicate that NaSbS2 forms from a binary system and interparticle ripening of nanoparticles to get a well-formed cubic shape.The electronic (3.31x10-10 Scm-1 (e-) and ionic (1.9 x 10-5 Scm-1) conductivities of the synthesized NaSbS2 NCs have been experimentally demonstrated using impedance and Dc polarization techniques. Overall this synthesis provide mechanistic insight and post synthetic evaluation of factors controlling the synthesis of alkali metal based chalcogenides materials behaving as MIECs.