The Customization of Phosphorus Terminal for MXene Materials by Photothermal Effect Toward High-Performance Zn-Ion Hybrid Supercapacitors

MXene materials exhibit outstanding pseudocapacitive performance, holding great potential for application in zinc-ion hybrid supercapacitors (Zn-HSCs). Exploring the effect of the surface terminal regulation on the performance of MXene is crucial yet challenging. In this study, the phosphorus-terminal groups (P─C and P─O) with a P concentration of 2.71 at% are successfully tailored and interlayer spacing is enhanced during the ultraviolet light irradiation process of Ti₃C₂T_x MXene, which is the first report of photoinduced P-doped MXene modification. Density functional theory calculations show that P doping is more likely to be adsorbed by ─O groups than to replace Ti vacancy, and the stability of the MXene electrode can be improved by the introduction of a phosphorus terminal. The resulting P-doped Ti₃C₂T_x MXene shows a significant increased pseudocapacitance performance, achieving superior results compared with traditional resistance furnace heating methods. The specific capacitance achieves 500.5 F g⁻¹, due to the ─P functional group and Ti atom double reoxidation sites. Furthermore, a Zn-HSC device of P-doped Ti₃C₂T_x exhibits a specific capacitance of 207.4 F g⁻¹ and energy densities of 56.5 Wh kg⁻¹. This study also provides valuable insights and a reference for the realization of phosphorus doping in other MXene materials.