Bimetallic Sulfide MCdS Modified with TiO2 Nanoneedle Cocatalyst for Enhancing Photocatalytic H2-evolution

Metal ion doping and composite materials preparation are the effective means to improve the activity of CdS photocatalysts. In this work, TiO2/MCdS (M = Zn, Ni) were synthetized by two steps hydrothermal method. The morphology, elemental composition and optical properties of TiO2/MCdS photocatalysts were characterized via XRD, SEM, TEM, XPS and UV-Vis. Interestingly, TiO2 nanoneedles were able to grow inside ZnCdS particles, which caused a strong interaction between TiO2 and ZnCdS was formed. However, TiO2 nanoneedle and NiCdS were not closely combined. As a result, the TiO2/ZnCdS (581.8 mu mol center dot g(-1)center dot h(-1)) possessed the optimal H-2 production rate and showed a 1.5-fold improvement compared to TiO2/NiCdS. This improvement of photocatalytic activity was mainly attributed to the effective separation of photogenerated electron hole pairs and the synergistic catalysis of water decomposition into hydrogen by TiO2 nanneedle-assisted catalyst. Thus, metal ion doping and TiO2 nanoneedle as cocatalyst could improve the photocatalytic H-2 production activity of CdS more effectively.