Solar-light driven water splitting to hydrogen and oxygen without sacrificial agents has gained tremendous attention due to the clean and renewable energy supply of the future. Herein, we report construction of Co3O4 quantum dots (QDs)/TiO2 nanobelts (NBs) hybrids via a facile hydrothermal method for simultaneous H-2 and O-2 productions from pure water, with high evolution rates of 41.8 and 22.0 mu mol h(-1) g(-1), respectively, which are significantly enhanced compared with TiO2 NBs and Co3O4 materials. The Co3O4 QDs not only improve light sensitivity but also change the work function of TiO2, promoting the transfer of electrons from TiO2 to Co3O4 QDs and H-2 generation on the surface of Co3O4 QDs. Moreover, the size effect of Co3O4 QDs (similar to 3 nm) facilitates the electron trapping due to the shorter pathway, and the generation of heterojunctions favors to suppress the recombination of photo-excited carries.