Ionic liquid assisted sonochemical synthesis of NiS submicron particles

A novel synthesis methodology is reported for the preparation of NiS submicron particles in a green solvent 1-butyl-3methylimidazolium tetrafluoroborate (BMImBF4) ionic liquid (IL), using ultrasonic sonochemical technique. Structural, morphological and optical properties of nickel sulfide powders were obtained by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and diffuse reflectance spectroscopy (DRS). Composition was corroborated by energy dispersive X-ray spectroscopy (EDXS), both in the SEM and in the TEM. Regular shape particles were obtained under high-intensity ultrasonic irradiation for 105 min from the reaction between nickel nitrate and thioacetamide in ethanol/BMImBF4 (80:20), respectively. After vacuum annealing treatment at 180 °C overnight, spherical crystalline NiS particles were observed. The powders showed a band gap of 0.74 eV.