Surface Phosphorus Grafting of Ti3C2Tx MXene as an Interface Charge “Bridge” for Efficient Electrocatalytic Hydrogen Evolution in All-pH Media

The interface electronic structure of heterogeneous catalysts can be modulated by changing the surface coordination configuration, which is crucial to their catalytic activity. Herein, a surface phosphorus-grafted Ti₃C₂T_x MXene platform anchored with an MoS₂ nanoflake heterojunction electrocatalyst was assembled through a simple phosphorus-hydrothermal method. An interface charge “bridge” has been created by grafting uniform P atoms coordinated with the surface O atoms of Ti₃C₂T_x (P-Ti₃C₂T_x), resulting in an interface charge-transfer channel between P-Ti₃C₂T_x and MoS₂. Based on the ultrafast transient absorption spectroscopy, the fastest electron-transfer kinetics from P-Ti₃C₂T_x to MoS₂ (1.7 ps) and the slowest electron–hole recombination speed (28 ps) were obtained over MoS₂@P-Ti₃C₂T_x than those over MoS₂@O-Ti₃C₂T_x and MoS₂@OP-Ti₃C₂T_x. Benefiting from the lower carrier transport activation energy, MoS₂@P-Ti₃C₂T_x exhibited the stirring electrocatalytic activity toward hydrogen evolution in all-pH media, which delivered three low overpotentials of 48.6, 63.2, and 70.5 mV at 10 mA cm^–2 toward the hydrogen evolution in alkaline, acid, and neutral media, respectively. Grafting an atomic scale “bridge” to create an electron-transfer channel proposes a new strategy to design an efficient pH-universal hydrogen evolution heterojunction electrocatalyst.