Influence of precursor crystallinity on photocatalytic activity of PdS/CdS-ZnS

In this work we present the synthesis and the photocatalytic activity of PdS/CdS-ZnS composites. The photocatalysts were obtained in hydrothermal conditions at 170 degrees C from zinc sulphides as sulphide source. The products were characterized by powder X-ray diffraction scanning electron microscopy, energy-dispersive X-ray, transmission electron microscopy, UV-visible and photoluminescence spectroscopies. From Tauc plot the optical energy gap was found to be nearly 2.40 eV. Experiments for hydrogen evolution were conducted in sulfide/sulfite aqueous solution under visible light. The size of photocatalyst nanoparticles and the efficiency of water splitting reaction increases with increasing of ZnS precursor crystallinity. The maximum value for hydrogen evolution rate is 3.8 mmol.g(-1)h(-1), for the sample with the highest crystallinity.