Orbital Hybridization Dominates the Enhanced Polarization Response Arising From Interlayer Coupling in Ti3C2Tx MXene.

Interlayer engineering plays a crucial role in the electronics, electromagnetics, and microwave engineering properties of two-dimensional materials. However, the lack of clear clarification of the complex coupling mechanisms has become a key bottleneck in guiding further performance improvement. Here, we take the intercalation of alkaline earth metal cations into MXene as a model system, exploring the dynamics, electronics, and crystal structure evolution triggered by different ionic properties. Experimental and computational results indicate that the interfacial electronic reconstruction driven by orbital hybridization is the dominant mechanism of the interlayer coupling effect. The desolvation behavior facilitates sustained electronic reconstruction, while the defects induced by stress accumulation adversely hinder in-plane electron transport. We further demonstrate this coupling in the dielectric domain: strong electron-gas-like polarization of Ca─O─Ti effectively enhances otherwise negligible microwave absorption of intrinsic MXene by 6.08 GHz. Further investigations into universality demonstrate the potential extension of this strategy to other members of the MXene family. This work reveals the specific mechanism underlying the interlayer coupling strategy and provides an example for the development of dielectric and electromagnetic devices.