Synthesis of ZnS nanoparticles by spray pyrolysis: Morphology control using the same precursors in different reactor systems

Nanoparticles of zinc sulfide, a II-VI semiconductor with a band gap in the near UV region, have potential applications in solar cells, displays, photocatalysis, bioimaging, and other fields. We have prepared ZnS nanoparticles through spray pyrolysis using zinc acetate and thiourea as precursors. For these same precursors, we used different reaction systems to produce nanoparticles with different size and properties. In one system, the precursors were premixed and heated together in a single reaction line. The particles produced in this system ranged from tens to hundreds of nanometers in diameter, and in most cases they were hollow or porous. In the other system, two separate atomizers and reaction lines have been used for the two precursors. Therefore, the two precursors were evaporated and heated in different lines and were mixed as vapors. Smaller (below 20 nm diameter), dense particles of irregular geometry were obtained in this system. Moreover, in this second system, particles of ZnO, ZnS, and intermediate compositions can be produced.