Synthesis-controlled structure-kinetics relationships in Ti3C2Tx/ZIF-67 MXene-MOF hybrids for electrochemical energy storage.

MXene/metal-organic framework (MOF) hybrids enable tunable electrode architectures and charge-storage kinetics, but synthesis-structure-electrochemical relationships remain insufficiently understood. Here, Ti3C2Tx/ZIF-67 hybrids were prepared through solution-assisted chemical hybridization and mechanochemical processing to establish synthesis-route-dependent structure-kinetics relationships. The chemical route preserves a comparatively ordered lamellar Ti3C2Tx architecture with ZIF-67 associated with exposed surfaces and locally separated lamellar regions, whereas mechanochemical processing produces fragmented, roughened, and edge-enriched Ti3C2Tx domains with more uniformly dispersed ZIF-67. X-ray diffraction reveals systematic modification of the average Ti3C2Tx stacking environment rather than uniform crystallographic interlayer expansion, while complementary Raman and X-ray photoelectron spectroscopy indicate greater local structural/surface disorder and altered coordination environments following mechanochemical processing. Under controlled low-mass-loading conditions in 3 M KOH, the optimized Ti3C2Tx/ZIF-67 (5 : 2.5) hybrid delivers an areal capacitance of ∼68 mF cm-2 (∼45 F g-1), compared with ∼36 mF cm-2 (∼24 F g-1) for pristine Ti3C2Tx. b-Value and Dunn analyses reveal mixed surface-controlled and diffusion-associated charge storage, with the relative contributions evolving systematically with scan rate and hybrid architecture. Electrochemical impedance analysis further indicates improved interfacial charge-transfer characteristics following hybridization. The optimized hybrid retains 88.9% of its initial capacitance with ∼98.6% coulombic efficiency after 5000 cycles, demonstrating reasonable electrochemical durability. Collectively, the structural, spectroscopic, and electrochemical results establish a synthesis-route-dependent structure-kinetics relationship in Ti3C2Tx/ZIF-67 hybrids, while avoiding attribution of the observed spectroscopic changes to quantitatively resolved atomic-scale defects. These findings provide a mechanistically grounded framework for engineering MXene/MOF architectures through controlled structural organization and processing-induced surface restructuring.