Spatial charge separation has already been realized between different facets of a single crystal. However, how the photogenerated charges distribute on one facet of a single crystal is still unknown. In this work, we found that the distribution of photogenerated charges on a SrTiO3 nanocube varies with the light intensity. Photogenerated holes tend to transfer to the edges and corners of the crystal under weak illumination, indicating that a spatial charge separation takes place on the same facet of the SrTiO3 nanocube. Based on this effect, oxidation and reduction cocatalysts can be respectively photodeposited on the edges and central areas of one facet. The separated dual-cocatalysts lead to a remarkable enhancement in photocatalytic overall water splitting. These findings reveal that the spatial charge separation can happen even on the same facet.