Nitrogen-Doped Carbon/Ti ₂ AlC MAX Phase Interfaces for Enhanced Conductivity and Active Site Accessibility in Neutral Electrolyte

Electrochemical processes in neutral electrolytes are inherently constrained by limited proton availability and sluggish charge-transfer kinetics, making interface engineering a critical strategy for performance enhancement. To address these challenges, this study demonstrates a tailored interfacial approach to regulate charge transfer and electrolyte accessibility by functionalizing the Ti₂AlC MAX phase with polydopamine, followed by carbonization to engineer nitrogen-doped carbon/Ti₂AlC MAX phase interfaces. The surface modification results in a heteroatom-rich environment with abundant active sites and enhanced surface polarity, as confirmed by X-ray photoelectron spectroscopy. The electrochemical behavior was systematically evaluated to deconvolve the relationship between surface modification and electrochemical performance. Electrochemical impedance spectroscopy reveals a significant reduction in the charge-transfer resistance. The synergistic interaction between the N-doped carbon and the Ti₂AlC MAX phase shows an approximately 65% reduction in the Tafel slope, indicating substantially improved hydrogen evolution kinetics and also enhanced specific capacitance compared to the pristine Ti₂AlC MAX phase. These results highlight the crucial role of surface functionalization in tailoring interfaces that are effective to overcome kinetic barriers in neutral media, providing a methodological framework for designing advanced electrode interfaces in sustainable electrochemical systems.