Phase‐Controlled Synthesis of High‐Bi‐Ratio Ternary Sulfide Nanocrystals of Cu1.57Bi4.57S8 and Cu2.93Bi4.89S9

摘要: High Bi-ratio ternary sulfides have been recently reported as superior thermoelectric materials. However, the synthesis of high Cu-Bi-S nanocrystal remains a challenge. Reported here are and characterization three-phase nanocrystals with nominal chemical formulae Cu1.57 Bi4.57 S8 , Cu2.93 Bi4.89 S9 Cu3 BiS3 . The samples were prepared using Bi2 S3 precursor by varying amount type Cu2-x S (i. e. Cu2 or Cu7.2 S4 ) reactants. TEM images reveal that two new crystalized having nanorod morphology radii approximately 50 nm lengths 200 nm. XPS results indicate valence states Bi in both phases +3 viable oxidation for Cu. UV-Vis-NIR absorption spectroscopy reveals narrow direct bandgaps 1.12 1.27 eV respectively. Besides, this method could also be applied to synthesize phase nanoplate morphology. as-synthesized show Cu/Bi ratio-dependent photoresponsive properties. This study not only reports structure bandgap sulfides, which discovered mineral previously, but provides an efficient synthesizing Bi-rich chalcogenide nanocrystals.