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

Cobalt sulfide quantum dots (CoSx QDs) modified TiO 2 nanoparticles are prepared with a precipitation-deposition method using TiO 2 , 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 H 2 O, thus enhancing the separation of the e − /h + pairs and the photocatalytic H 2 production activity of TiO 2 . The amount of CoSx exhibits an optimum value at about 5% (mole ratio to TiO 2 ), at which the H 2 production rate achieves 838 μmol h −1  g −1 using ethanol as the sacrificial reagent. This exceeds that of the pure TiO 2 by more than 35 times.