CdS-sensitized K2Ti4O9 composite for photocatalytic hydrogen evolution under visible light irradiation

CdS-sensitized K2Ti4O9 composite photo-catalysts (hereafter designated as CdS/K2Ti4O9) were prepared by a facile deposition-precipitation method. The samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), ultraviolet–visible diffuse reflectance spectra (UV–vis DRS), and X-ray photoelectron spectroscopy (XPS). The photo-catalytic activities for hydrogen evolution were investigated under visible light irradiation. The CdS particles, which were scattered on the surface of K2Ti4O9, had a relative uniform size distribution around approximately 50 nm, and the absorption edge of K2Ti4O9 shifted to the visible light region after the deposition of CdS. The composite photo-catalyst loaded with 25 wt.% CdS synthesized via precipitation method showed the highest photo-catalytic activity. The photocatalytic reaction parameters, such as the dosage of catalyst, and concentrations of sacrificial reagents, were studied and optimized. The mechanism of separation of the photo-generated electrons and holes at the CdS/K2Ti4O9 composite was also discussed.

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► CdS was deposited on the surface of K2Ti4O9 via a precipitate method.
► The deposition of CdS greatly increase the visible light absorption for K2Ti4O9.
► The composite photo-catalysts exhibited enhanced photocatalytic hydrogen evolution.