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<p>Mo<sub>2</sub>CT<sub><i>x</i></sub> MXene is a novel two-dimensional material, which is generally made by the etching of inorganic acid solutions, such as hydrofluoric acid (HF) or hydrochloric acid (HCl). Those solutions are always corrosive and hazardous. In this paper, a mild organic acid, acetic acid (CH<sub>3</sub>COOH), was selected to synthesize Mo<sub>2</sub>CT<sub><i>x</i></sub> MXene. 30 mL acetic acid (HAc) with the concentration of 13 mol/L was mixed with 2 g acetate (CH<sub>3</sub>COONa or CH<sub>3</sub>COOK) and 10 mL water to make etching solution (NaAc+HAc or KAc+HAc). In the solution, the concentration of CH<sub>3</sub>COO<sup>−</sup> was 10 mol/L, the concentration of Na<sup>+</sup>/K<sup>+</sup> is 0.6/0.5 mol/L. The pH value is 2.8. Mo<sub>2</sub>CT<sub><i>x</i></sub> was obtained by hydrothermal etching at 240 °C for 1 d. Compared with the general method of HF etching, the etchant is milder and the etching process is safer. On the surface of Mo<sub>2</sub>CT<sub><i>x</i></sub> nanosheet made by this method, acetate group (CH<sub>3</sub>COO<sup>−</sup>) was adsorbed as termination, which is larger than the F/O/OH termination of that made by general HF etching. The lattice parameter <i>c</i> (LP<i>c</i>) of Mo<sub>2</sub>CT<sub><i>x</i></sub> etched with NaAc+HAc/KAc+HAc is 21.09 Å/20.89 Å. Moreover, the specific surface areas of the samples etched by NaAc+HAc and KAc+HAc were 18.1 m<sup>2</sup>/g and 14.1 m<sup>2</sup>/g, respectively, which were much larger than those etched by conventional methods. As the anode of lithium-ion battery, the specific capacity under current density of 100 mA/g at 100th cycle was 108 mA·h/g, which is higher than the capacity of samples made by general HF etching. This work reports a novel method to make Mo<sub>2</sub>CT<sub><i>x</i></sub> MXene by the solution of mild acetic acid. The samples made by this method had very high specific surface area and relatively high lithium-storage performance.</p>

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Preparation of Mo2CTx MXene with high specific surface area by etching of acetic acid/acetate solution

  • 期刊论文

  • 发表日期：

    2025年10月1日

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  • Guang-lei Zhang,
  • Ya-qiong Du,
  • Yi-tong Guo,
  • Han Liu,
  • Li-bo Wang,
  • Ji-zhou Jiang,
  • Ai-guo Zhou

摘要

Mo2CTx MXene is a novel two-dimensional material, which is generally made by the etching of inorganic acid solutions, such as hydrofluoric acid (HF) or hydrochloric acid (HCl). Those solutions are always corrosive and hazardous. In this paper, a mild organic acid, acetic acid (CH3COOH), was selected to synthesize Mo2CTx MXene. 30 mL acetic acid (HAc) with the concentration of 13 mol/L was mixed with 2 g acetate (CH3COONa or CH3COOK) and 10 mL water to make etching solution (NaAc+HAc or KAc+HAc). In the solution, the concentration of CH3COO− was 10 mol/L, the concentration of Na+/K+ is 0.6/0.5 mol/L. The pH value is 2.8. Mo2CTx was obtained by hydrothermal etching at 240 °C for 1 d. Compared with the general method of HF etching, the etchant is milder and the etching process is safer. On the surface of Mo2CTx nanosheet made by this method, acetate group (CH3COO−) was adsorbed as termination, which is larger than the F/O/OH termination of that made by general HF etching. The lattice parameter c (LPc) of Mo2CTx etched with NaAc+HAc/KAc+HAc is 21.09 Å/20.89 Å. Moreover, the specific surface areas of the samples etched by NaAc+HAc and KAc+HAc were 18.1 m2/g and 14.1 m2/g, respectively, which were much larger than those etched by conventional methods. As the anode of lithium-ion battery, the specific capacity under current density of 100 mA/g at 100th cycle was 108 mA·h/g, which is higher than the capacity of samples made by general HF etching. This work reports a novel method to make Mo2CTx MXene by the solution of mild acetic acid. The samples made by this method had very high specific surface area and relatively high lithium-storage performance.