Facile synthesis of ultrathin γ-Fe2O3 magnetic nanosheets rich in oxygen vacancies and their photocatalytic activity for water oxidation

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-Fe 2 O 3 nanosheets (Fe 2 O 3 -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-Fe 2 O 3 bulk, Fe 2 O 3 -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 Fe 2 O 3 -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.