RETRACTED: One-pot synthesis of O-doped BN nanosheets as a capacitive deionization electrode for efficient removal of heavy metal ions from water (Publication with Expression of Concern. See vol. 7, pg. 2919, 2019) (Retracted article. See vol. 7, pg. 20445, 2019)

O-Doped BN nanosheets with a thickness of 1.033 nm were prepared via the direct reaction of CuB23 with NOCl at room temperature in ionic liquids. It had a large high specific surface area of 858 m(2) g(-1), and showed a high electrical conductivity of 34.3 S m(-1) and a good specific capacity of 187 F g(-1). Meanwhile, the obtained sample demonstrated excellent performance as the electrode material for capacitive deionization (CDI) to remove Cd2+ from water in a wide range of concentrations from 0.05 to 600 ppm with a maximum adsorption capacity of 2281 mg g(-1). It is attributed to its unique structural characteristics and the ability of its NO-groups to coordinate Cd2+ which promotes the electrosorption. More importantly, it exhibited outstanding capability for the total, rapid, and simultaneous removal of multiple metal ions (Zn2+, Cd2+, Pb2+, Ni2+, Co2+, Cu2+, Mg2+, Ca2+, Fe2+, Fe3+ and Na+) by CDI within 20 min. These results suggest promising applications of our BNO nanosheets for water purification and water-softening devices based on CDI.