▎ 摘　　要

NOVELTY - Preparing amorphous oxygen-doped boron nitride nanosheet, comprises (i) adding 50 mg amorphous graphene-like copper boride nanosheets into 50 ml 1-butyl-3-methylimidazolium chloride solution to obtain suspension, (ii) adding 1.25 g nitrosyl chloride into the suspension, and reacting by stirring continuously at 298 K for 30 minutes, (iii) absorbing generated chlorine gas using 1 M sodium hydroxide solution, and (iv) washing the obtained product with 0.01 M dilute hydrochloric acid, and washing with deionized water and absolute ethyl alcohol respectively for 3 times, and (v) drying at 60 degrees C. USE - The boron nitride nanosheet is useful as electrode for electro-adsorption of heavy metal ions in water based on capacitive deionization technology in water purification and water softening fields. ADVANTAGE - The boron nitride nanosheet: has unique structure and coordination capability; and removes multiple heavy metal ions (preferably cadmium(II) and zinc(II) ions) in water completely, quickly and simultaneously. DETAILED DESCRIPTION - Preparing amorphous oxygen-doped boron nitride nanosheet, comprises (i) adding 50 mg amorphous graphene-like copper boride (CuB23) nanosheets into 50 ml 1-butyl-3-methylimidazolium chloride ((BMIM)Cl) solution to obtain suspension, (ii) adding 1.25 g nitrosyl chloride into the obtained suspension, and reacting by stirring continuously at 298 K for 30 minutes, (iii) absorbing generated chlorine gas using 1 M sodium hydroxide solution, and (iv) washing the obtained product with 0.01 M dilute hydrochloric acid, and washing with deionized water and absolute ethyl alcohol respectively for 3 times, and (v) drying at 60 degrees C.