In-Depth Study of ZnS Nanoparticles Surface Properties with a Combined Experimental and Theoretical Approach

ZnS nanoparticles (NPs) were synthesized using a simple, green and reproducible hydrothermal method. TEM micrographs shown polyhedral NPs having an average diameter of 21 nm, while the XRD analysis is consistent with the exclusive presence of cubic ZnS, whereas no oxide could be detected. A comprehensive characterization of the NPs surface was accomplished through XPS, DRIFT, Raman, and TGA-DSC, showing a fairly pure ZnS composition and a remarkable amount of adsorbed water molecules. The interaction capabilities of the surface were probed in-situ by DRIFT using small molecules (CO, CO2, methanol, pyridine) as molecular probes. The same interactions were also theoretically studied with density functional calculations using a slab model based on the sphalerite ZnS (110) surface. By comparing theoretical and experimental vibrational shifts, insights on the nature of the interaction between molecular probes and surfaces were obtained. Water was found to alter both the structure as well as the reactivity of t...