Oxygen evolution reaction (OER) is the bottleneck of photocatalytic water splitting due to the slow four-electron transfer kinetics, and the construction of ultrathin materials is considered to be an effective means to solve the above problem. Herein, ultrathin γ-Fe2O3 nanosheets (Fe2O3-NS) were prepared by a facile solution reduction-low temperature calcination method. The prepared photocatalyst has a leaf-like morphology with an average thickness of 2.0 nm and a large number of slit-like pores. Compared with γ-Fe2O3 bulk, Fe2O3-NS exhibits excellent photocatalytic OER activity. The apparent quantum yield (AQE) and oxygen yield (measured at 420 nm) are 12.95% and 57.04%, respectively. The OER efficiency is superior to those reported iron oxide photocatalysts. This excellent performance may benefit from the ultrathin porous structure, appropriately narrow bandgap, and abundant oxygen vacancies. In addition, the photocatalyst shows good cycling stability, retaining 91.5% of the initial capacity in the fifth cycle test, which may be attributed to the magnetic cycling capability and good structural stability. This study confirms that Fe2O3-NS is a competitive candidate material for photocatalytic oxygen evolution and provides ideas for the design and construction of other defect-rich metal oxide nanosheets.
