Dependence of Transition-Metal Telluride Phases on Metal Precursor Reactivity and Mechanistic Implications.

Modern bottom-up synthesis to nanocrystalline solid-state materials often lacks the reasoned product control that molecular chemistry boasts from having over a century of research and development. In this study, six transition metals including iron, cobalt, nickel, ruthenium, palladium, and platinum were reacted with the mild reagent didodecyl ditelluride in their acetylacetonate, chloride, bromide, iodide, and triflate salts. This systematic analysis demonstrates how rationally matching the reactivity of metal salts to the telluride precursor is necessary for the successful production of metal tellurides. The trends in reactivity suggest that radical stability is the better predictor of metal salt reactivity than hard-soft acid-base theory. Of the six transition-metal tellurides, the first colloidal syntheses of iron and ruthenium tellurides (FeTe2 and RuTe2) are reported.

Synthesis of vulcanite (CuTe) and metastable Cu1.5Te nanocrystals using a dialkyl ditelluride precursor.

This study demonstrates that a dialkyl ditelluride reagent can produce metastable and difficult-to-achieve metal telluride phases in nanocrystal syntheses. Using didodecyl ditelluride and without the need for phosphine precursors, nanocubes of the pseudo-cubic phase (Cu1.5Te) were synthesized at the moderate temperature of 135 °C. At the higher temperature of 155 °C, 2-D nanosheets of vulcanite (CuTe) resulted, a nanomaterial in a phase that has not been previously achieved through thermal decomposition methods. Materials were characterized with TEM, powder XRD and UV-Vis-NIR absorbance spectroscopy.