Nh4hco3

LiOH·H₂O (99.0%, AR) and ethanol (99.7%, AR) were purchased from Aladdin. MnSO₄·H₂O (99.0%, AR), NH₄HCO₃ (21.0%, AR), NH₃·H₂O (25%, AR), and H₂SO₄ (98.0 wt.%) were supplied by XiLong Chemical Co. Ltd. All reagents were used without further purification. The spherical MnCO₃ was first prepared by a general chemical precipitation method. In a typical synthesis, 0.3042 g MnSO₄·H₂O and 1.4231 g NH₄HCO₃ were dissolved in 45 mL deionized water and 5 mL ethanol, respectively, to form a transparent solution. After the complete dispersion of the MnSO₄ and NH₄HCO₃ solutions, the NH₄HCO₃ solution was added to the MnSO₄ solution rapidly with vigorous stirring. A certain amount of NH₃·H₂O (10.0% v/v.) or H₂SO₄ (10.0% v/v.) was then added dropwise to adjust the pH value of the suspension to 7.5. The milky white suspension was stirred for 3 h at room temperature and maintained for 5 h. The powder was obtained by filtrating, washing, and drying in the air at 80°C for 24 h to obtain spherical MnCO₃ precursors.