MXenes, a new family of two-dimensional materials, have been recognized as promising candidates for supercapacitors because of their unique chemical and physical properties. It has been proven that the terminal groups on MXenes play a decisive role in the pseudocapacitance. In this study, we report a highly efficient strategy to remove the –F terminal groups of Ti₃C₂T_x. Our initial purpose was to explore the application of Ti₃C₂T_x in sodium-ion batteries, whereas we found that almost all the –F terminal groups on Ti₃C₂T_x could be eliminated by reaction with Na metal at high temperature, and abundant terminal –O was introduced after the subsequent washing step. The mechanism involved is clarified by combining systematical spectra analysis and density functional theory (DFT) calculations. In addition, the modulated Ti₃C₂T_x MXene shows an extraordinarily high specific capacitance of 521 F·g⁻¹ (at scan rate of 2 mV·s⁻¹) or 578 F·g⁻¹ (at a discharge rate of 1 A·g⁻¹) in 1 м H₂SO₄, and 92% capacity could be retained even after 10000 cycles. This study should provide new insight into the surface chemistry of MXenes and facilitate its applications in a variety of fields.

MXenes 是一种新的二维材料家族，由于其独特的化学和物理特性，已被公认为超级电容器的有希望的候选者。已经证明，MXenes 上的末端基团在赝电容中起决定性作用。_{在本研究中，我们报告了一种去除 Ti 3} C ₂ T _x的-F 末端基团的高效策略。我们最初的目的是探索 Ti ₃ C ₂ T _x在钠离子电池中的应用，而我们发现 Ti ₃ C ₂ T _{x上几乎所有的 -F 端基}可以通过在高温下与金属钠反应消除，并且在随后的洗涤步骤后引入了丰富的末端-O。通过结合系统光谱分析和密度泛函理论 (DFT) 计算来阐明所涉及的机制。此外，调制的 Ti ₃ C ₂ T _x MXene 显示出 521 F·g ^-1（扫描速率为 2 mV·s ^-1）或 578 F·g ^-1（放电速率为1 A·g ^-1 ) in 1 м H ₂ SO ₄，即使在 10000 次循环后仍可保留 92% 的容量。这项研究应该为 MXenes 的表面化学提供新的见解，并促进其在各个领域的应用。