Engineering Mo₂TiC₂T_x MXene Electrocatalyst via Metal-Ion Intercalation Toward Efficient Hydrogen Evolution Reaction

Developing highly efficient, stable, and low-cost nonprecious metal electrocatalysts for the hydrogen evolution reaction (HER) is critical for scalable green hydrogen production. Herein, we designed a powerful metal ion intercalation strategy to fabricate high-performance MXene-based HER catalysts. Systematic studies on Mo₂TiC₂T_x (T_x= O, OH, F) intercalated with Co²⁺, Mn²⁺, and Ni²⁺ ions reveal that all three intercalants could induce interlayer expansion to expose active sites. Further in-depth investigation reveals that the incorporation of Ni²⁺ in the Mo₂TiC₂T_x forms NiOMo bonds, creating a strong electronic interaction that drives charge transfer from Ni atoms to Mo and O atoms. This results in an electron-rich Mo₂TiC₂T_x surface, thereby enhancing its catalytic activity. As a result, the optimal 1 mM Ni²⁺-Mo₂TiC₂T_x catalyst yields exceptional HER performance in 0.5 M H₂SO₄, requiring an overpotential of only 93 mV to achieve 10 mA cm^-2 and demonstrating remarkable stability over 700 h of continuous operation, which confirms its high activity and excellent durability. This article proposes an innovative strategy for designing MXene-based catalysts through the synergistic control of interlayer spacing and electronic structure.