Synthesis of trigonal selenium nanorods by electrodeposition from an ionic liquid at high temperature

Abstract

We report on the electrodeposition of trigonal selenium (t-Se) nanorods from 1-ethyl-3-methylimidazolium tetrafluoroborate/chloride ([C 2mim][BF 4]/[C 2mim]Cl) at high temperature (T > 100 °C). It is shown that the Se 4+ precursor salt significantly influences the electrochemical behaviour, as well as the phase, morphology and crystallinity of the Se deposits. Amorphous selenium (a-Se) films are deposited from [C 2mim][BF 4]/[C 2mim]Cl-SeCl 4 whereas high aspect ratio single-crystalline trigonal selenium nanorods are formed from [C 2mim][BF 4]/[C 2mim]Cl-SeO 2. The t-Se nanorods are characterized by XRD, SEM, TEM and Raman spectroscopy and the growth mechanism of the single-crystalline t-Se nanorods from a-Se particles during the electrodeposition process is elucidated. The crystallinity of the t-Se nanorods is improved by increasing the temperature from 100 to 160 °C. Photoelectrochemical measurements performed in the ionic liquid confirm the p-type conductivity of the t-Se nanorods.