Nitrogen‐Directed Ti ₃ C ₂ T _x Enabling Rapid Proton Storage for Printed in‐Plane Micro‐Pseudocapacitors

ABSTRACT MXene‐based proton pseudocapacitors are promising candidates for microscale electronic devices due to their superior portability and high‐power density, yet their advancement is constrained by the scarcity of efficient electrode materials. Herein, a nitrogen‐directed Ti ₃ C ₂ T _x MXene with substitution of terminal functional groups by nitrogen is proposed as a high‐efficiency electrode material for proton pseudocapacitors. This strategy introduces multiple surface‐active sites and a new pathway for fast proton storage for achieving high specific capacitance. Impressively, a nitrogen‐directed proton storage mechanism is unraveled in the terminal N groups can preferentially interact with protons and lower the diffusion energy barrier toward adjacent active‐sites, substantially facilitating the storage of protons. As a result, the N300‐Ti ₃ C ₂ T _x delivers excellent capacitance retention of 84.48% after 30,000 cycles at 2 A g ⁻¹ . Furthermore, in‐plane proton pseudocapacitors are fabricated via direct ink writing, which shows great compatibility with various connection configurations, validating the superior potential in application feasibility of the N‐directed Ti ₃ C ₂ T _x on proton storage.