We experimentally demonstrated that spatial charge separation can take place between the {010} and {001} facets of Bi2WO6 microplates. Further assembly of the reduction and oxidation cocatalysts leads to a remarkable enhancement of photocatalytic water oxidation activity in the presence of Fe3+ ions while the reverse oxidation of Fe2+ to Fe3+ ions is totally inhibited. The origin of the driving force is theoretically proven to be the difference in surface work function between the co-exposed facets, which shows a feasible strategy for developing efficient photocatalysts for solar energy conversion.