Robust Ti─N Interface in MXene‐C ₂ N Heterostructures for Ultra‐Durable Acidic Hydrogen Evolution

Durable, cost‐effective hydrogen evolution in acidic media requires electrocatalysts that can rival platinum in catalytic activity and stability. We report atomically engineered Ti 3 C 2 T x @C 2 N heterostructure exploiting robust Ti–N interfacial bonding and electronic coupling to deliver platinum‐like performance without noble metals. The hybrid catalyst exhibits ultralow overpotential of 42 mV at 10 mA cm −2 and Tafel slope of 36 mV dec −1 , approaching commercial Pt/C benchmarks. More importantly, it maintains stable operation over 550 h at 100 mA cm −2 in corrosive acidic medium, far surpassing Pt/C. Structural analyses and density functional theory reveal that Ti─N interface optimizes hydrogen adsorption free energy and lowers the kinetic barrier for O─H bond cleavage, while the porous C 2 N scaffold enhances charge transport and active site accessibility. This synergistic structural and electronic design establishes a generalizable strategy for robust heterostructures, advancing scalable platinum‐free electrocatalysts for next‐generation proton exchange membrane electrolyzers and other energy conversion technologies.