Two-dimensional metal oxide nanostructures,such as nanoplates,nanowalls,and nanosheets,have received further attentions in recent years,due to their outstanding properties resulted from the small thickness and quantum size effects.In this work,lanthanum oxide nanosheets with the thickness of 56 nm had been successfully prepared by an originally simple method of carbon dioxide carbonation;the preparation process was green without using surfactants and detergent.The X-ray diffraction,transmission electron microscopy,and scanning electron microscopy were used to characterize the products.Thermogravimetric-differential thermal analysis and FT-IR were introduced to prove that the lanthanum oxide precursor with lamellar morphology was La2(CO3)3 3H2O.The carbon dioxide carbonation method would provide significant benefits containing mild reaction conditions,high efficiency,low cost,and easy to realize large-scale production. Two-dimensional metal oxide nanostructures, such as nanoplates, nanowalls, and nanosheets, have received further attentions in recent years, due to their outstanding thickness due to the small thickness and quantum size effects. In this work, lanthanum oxide nanosheets with the thickness of 56 nm had been successfully prepared by an originally simple method of carbon dioxide carbonation; the preparation process was green without using surfactants and detergent. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy were used to characterize the products. Thermogravimetric- differential thermal analysis and FT-IR were introduced to prove that the lanthanum oxide precursor with lamellar morphology was La2 (CO3) 3 3H2O. The carbon dioxide carbonation method would provide significant benefits containing mild reaction conditions, high efficiency, low cost, and easy to realize large-scale production.