Cobalt sulfide quantum dots modified TiO2 nanoparticles for efficient photocatalytic hydrogen evolution

•CoSx/TiO2 heterojunction photocatalysts are synthesized.•The CoSx/TiO2 shows remarkable UV and visible light photocatalytic activity.•The hydrogen evolution rate was greatly improved.•The intimate contact of the phases promotes the charge transfer and separation.

Cobalt sulfide quantum dots (CoSx QDs) modified TiO2 nanoparticles are prepared with a precipitation-deposition method using TiO2, cobalt acetate and sodium sulfide as the precursors. CoSx QD acts as an effective cocatalyst, which accelerates the transfer of the photo-generated electrons and serves as the active site for the reaction between electrons and H2O, thus enhancing the separation of the e−/h+ pairs and the photocatalytic H2 production activity of TiO2. The amount of CoSx exhibits an optimum value at about 5% (mole ratio to TiO2), at which the H2 production rate achieves 838 μmol h−1 g−1 using ethanol as the sacrificial reagent. This exceeds that of the pure TiO2 by more than 35 times.

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