Unveiling Confined Proton Desolvation Dynamics in Interlayer‐Engineered MXenes

ABSTRACT The rational design of proton‐based energy storage systems requires a fundamental understanding of proton behavior under nanoscale confinement. Herein, we elucidate the desolvation dynamics and charge‐transfer mechanisms of confined protons within interlayer‐engineered Ti 3 C 2 T x MXenes through a combined theoretical and experimental approach. Density functional theory (DFT) calculations reveal that proton transport strongly depends on the interlayer spacing: when the gallery distance exceeds 0.6 nm, hydrated protons (H 5 O 2 + ) undergo efficient desolvation and interfacial charge transfer, whereas narrower spacing traps protons in a suspended, fully solvated state, thereby impeding charge transport. Guided by these insights, Mo‐doped MXenes (Mo‐MXene) with tunable interlayer spacing were synthesized, exhibiting enlarged galleries and enhanced surface charge density. The optimized Mo‐MXene‐based hybrid supercapacitors deliver a high volumetric energy density of 94.2 Wh L −1 at a power density of 398.9 W L −1 , and more importantly, maintain an impressive energy density of 74.0 Wh L −1 even at an ultrahigh power density of 156.7 kW L −1 . This study establishes interlayer spacing as a decisive structural parameter governing proton desolvation and electron‐transfer coupling, providing a universal design strategy for high‐rate, high‐capacitance proton‐based electrochemical energy storage systems.