Metal Sulfide Thin Films with Tunable Nanoporosity for Photocatalytic Applications

Metal xanthates are widely used as single-source precursors for the formation of metal sulfide thin films. In this study, we explore the length of the alkyl ligand as an efficient tool to control the formation and the nanoporosity of zinc sulfide thin films. The presented approach allows us to prepare highly porous thin metal sulfide films with potential applications in photocatalysis, whereby the nanoporosity is significantly enhanced with an increasing number of carbons in the alkyl chain of the metal xanthate precursors. To gain knowledge about the mechanisms leading to the changes in the nanoporosity, the thermal conversion process toward the porous films is studied in detail by time-resolved simultaneous grazing incidence small- and wide-angle X-ray scattering measurements using synchrotron radiation and thermogravimetric analysis. Thereby, we found that the structural changes during the early stages of the conversion process, which are distinctly influenced by the decomposition temperature of the metal xanthates, different growth regimes of the nanocrystals, and a mesophase formation, governed by the properties of the decomposition products of the metal xanthates, are mainly responsible for the changes of the structural properties and the nanoporosity of the final ZnS films.