Synthesis and photoactivity of nanostructured CdS–TiO2 composite catalysts

• CdS and TiO2 photocatalysts were synthesized without surfactant and at RT.
• CdS formation and properties depended on the Cd and S ratio in the precursor.
• pH affected the TiO2 formation and properties.
• The CdS–TiO2 ratio influenced the composite's photocatalytic activity.

In this paper, a series of nanostructured TiO2–CdS composite photocatalysts have been synthesized using an aqueous solution route at room temperature, and characterized with X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), UV–VIS absorption and Fourier transform infrared spectroscopy (FTIR). Their photocatalytic activities have been investigated on the degradation of methylene blue under simulated solar light irradiation. CdS shows the highest activity when the ratio of the starting materials Na2S to Cd(NO3)2 is close to 1.0, TiO2 shows the best activity when prepared under pH = 13.0, and the CdS/TiO2 composite with the molar ratio of TiO2 to CdS of 50 displays the highest activity.

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