Nanohybrid of two-dimensional tellurium and metal sulfotelluride for solar-driven photocatalytic hydrogen production from seawater

The use of sunlight radiation to cause the dissociation of seawater has tremendous promise as a green method for hydrogen production. Herein, tellurides and sulfotellurides of cadmium and zinc and solid solutions like CdxZn(1-x)SyTe(1-y) were synthesized by a coprecipitation method at room temperature. The prepared materials were tested as photocatalysts to produce H2 from seawater using lactic acid as a sacrificial reagent assisted by a solar simulator. All photocatalysts were active for hydrogen production from seawater and artificial sunlight. The cadmium-free photocatalyst (ZnSTe) was the most active one with a hydrogen production rate of 378.85 µmol g-1 h-1, followed by CdZnSTe (374.7 µmol g-1 h-1). The low sulfur content profoundly changes the UV-vis absorption spectra of the sulfotellurides, improving photocatalytic activity. XPS and TEM analysis revealed that the ZnSTe is composed of elemental tellurium nanosheets decorated with nano amorphous ZnTe and cubic phase ZnO. Thus, the p-n heterojunction formation between the ZnTe and ZnO improves the separation and migration rates of photogenerated carrier pairs, improving the solar-driven H2 production. Furthermore, the presence of 2D Te nanosheets dispersed in ZnSTe may contribute as support for charge transfer, which is essential in increasing photocatalytic activity.