Molecular oxygen activation is very important for photocatalytic degradation of organic pollutants. In this paper, Bi24O31Cl10 nanosheets with {1 0 0} facets exposure were successfully synthesized by hydromel method and characterized. The size of a single nanosheet is about 5 pm in width and 10-30 nm in thickness, which results in a large ratio of surface to thickness and higher exposure ratio of {1 0 0} facets. The Mott-Schottky test revealed that the conduction band minimum (CBM) of Bi24O31Cl10 is more negative than BiOCl due to the bismuth-rich strategy. And the photocatalytic results showed that as-synthesized Bi24O31Cl10 showed higher photocatalytic properties than BiOCl for activate molecular oxygen to generate superoxide radical (O-2 center dot(-)) under visible light (lambda >420 nm) irradiation, and generate hydroxyl radical (center dot OH) under UV-vis light irradiation. This strategy in this work may potentially be extended to other bismuth-based photocatalysts for molecular oxygen activation. (C) 2014 Elsevier B.V. All rights reserved.