A general method was elaborately developed for the synthesis of pit-rich metal oxide (TiO2, ZrO2 and HfO2) nanocrystals with metallocene dichlorides as precursors. Benefiting from the synergies in numerous pits, Schottky junctions and nitrogen doping, the hybrid nanostructures of pit-rich TiO2 nanocrystals with Ru loading and N doping exhibited enhanced solar water splitting.