The surface modification of MXene by heterogeneous atoms shows great potential in improving the charge storage capacity of MXene. Herein, a strategy of rapid in-situ phosphorus doping at low temperature is demonstrated for preparing functionalized Ti₃C₂T_x MXene (Ti₃C₂T_x-P) using sodium hypophosphate as phosphorus source. The phosphorus doping can increase the layer spacing of Ti₃C₂T_x and yield PO and PC bonds in Ti₃C₂T_x, resulting in more rapid paths for the migration of electrolyte ions into electrode and more active sites for pseudocapacitance effects. As flexible electrode of supercapacitor, the specific capacitance of Ti₃C₂T_x-P reaches as high as 476.9F g⁻¹ (745.4F cm⁻³), which is far larger than that of the raw Ti₃C₂T_x (344.4F g⁻¹, 438.5F cm⁻³). In addition, a flexible quasi-solid supercapacitor device assembled by Ti₃C₂T_x-P film shows high specific capacitance of 103F g⁻¹ at 5 mV s⁻¹. When the power density is 250 W kg⁻¹ and 10000 W kg⁻¹, the corresponding energy density reaches 15.8 Wh kg⁻¹ and 6.1 Wh kg⁻¹, respectively. Therefore, our work not only reveals the role of P atom doping in improving the structure, composition and electrochemical performance of Ti₃C₂T_x, but provides a method for surface modification and functionalization of MXene materials.

异质原子对 MXene 的表面改性在提高 MXene 的电荷存储能力方面显示出巨大的潜力。在此，展示了一种在低温下快速原位磷掺杂的策略，用于以连磷酸钠为磷源制备功能化的 Ti ₃ C ₂ T _x MXene (Ti ₃ C ₂ T _{x -P)。磷掺杂可以增加Ti 3} C ₂ T _x的层间距并在Ti ₃ C ₂ T _x中产生P O 和P C 键。，导致电解质离子迁移到电极的路径更快速，赝电容效应的活性位点更多。_{作为超级电容器的柔性电极，Ti 3} C ₂ T _x -P的比电容高达476.9F g ^-1 (745.4F cm ^-3 )，远大于原始Ti ₃ C ₂ T _x (344.4F g ^-1 , 438.5F cm ^-3 )。此外，由 Ti ₃ C ₂ T _x -P 薄膜组装的柔性准固态超级电容器器件在 5 mV s 时显示出 103F g ^{-1的高比电容-1}。当功率密度为250 W kg ^-1和10000 W kg ^-1时，相应的能量密度分别达到15.8 Wh kg ^-1和6.1 Wh kg ^-1。因此，我们的工作不仅揭示了P原子掺杂在改善Ti ₃ C ₂ T _x的结构、组成和电化学性能方面的作用，而且为MXene材料的表面改性和功能化提供了一种方法。