“Compulsory co-precipitation”, a Novel and Rational Route for the Synthesis of Nanomaterials; Mesoporous Zinc Sulfide as the First Case

Abstract In the present research work, a novel approach named as compulsory co-precipitation has been introduced for the synthesis of nanoparticles. In this approach a liquid in which the precursors of the target chemical compound are insoluble has been selected as the media of the synthesis reaction. Compulsory co-precipitation was employed for the synthesis of mesoporous zinc sulfide (ZnS) particles which normally were synthesized in the soluble atmospheres. The mesoporous ZnS particles with relatively large surface area were synthesized in the cyclohexane atmosphere as a non-solvent reaction media for Zn(NO3)2.6H2O and Na2S.5H2O precursors. Successful synthesis of cubic zinc-blende ZnS particles was confirmed by X-ray diffraction (XRD) analysis. Nitrogen adsorption-desorption analysis was exploited to elucidate the surface porosity characteristics of the particles. The results validated the formation of a mesoporous structure with the maximum specific surface area of about 191 m2.g-1, mean pore diameter of 2.6 nm, and pore volume of about 0.12 cm3.g-1. Forced solution of Zn2+ and S2- as a result of ultrasonic irradiation followed by immediate precipitation of the synthesized ZnS particles was proposed as the ZnS formation mechanism. Also the removal the by-product of the synthesis reaction during the post synthesis treatments was suggested as the main factor for the induction of porosity in the ZnS structure.