Enhancing the activity of a SiC–TiO2 composite catalyst for photo-stimulated catalytic water splitting

In this work, effort has been made to design an efficient catalyst for the photo-stimulated water splitting reaction, starting with the modification of TiO2 (P25) to enhance its activity. A SiC(1 wt%)–TiO2 composite material shows an activity as high as twice of that of TiO2. NiOx, an electron collector, promotes the activity of TiO2, while IrO2, a hole capturer, enhances the hydrogen evolution rate of SiC. A SiC(1 wt%)–NiOx/TiO2 three-component and an IrO2/SiC(1 wt%)–NiOx/TiO2 four-component composite materials produce 30% and 100% more H2 than the NiOx/TiO2 catalyst during the first 5 h, respectively, with ethanol used as the sacrificial reagent. Furthermore, the SiC(1 wt%)–NiOx/TiO2 catalyst is active under visible light, while the NiOx/TiO2 catalyst shows no activity under the same irradiation condition. 3C-SiC has a narrow band gap and its band edge well compensates that of the TiO2. The enhancing effect of dopants on the SiC(1 wt%)–TiO2 composite material is sensitive to the location of the modifiers, which further proves that an efficient separation of the charge carriers is crucial to the overall activity of the composite catalyst.

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► A non-metallic semiconductor is used as a promoter of TiO2 for water splitting.
► The SiC modified catalysts exhibit excellent activities in hydrogen evolution.
► The composite catalysts are active under visible light and enough stable.
► Directional movement of the charge carriers in the composites is proposed.