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

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.