Rare-Earth Ion Intercalation in Graphene via Thermal and Electrostatic Control.

Atomic-scale control and understanding the controlling strategy of ion intercalation are pivotal for advancing energy storage, quantum technologies, and adaptive electronics. While intercalation - the insertion of ions into layered materials - has transformative potential, the mechanisms driving it, particularly for rare-earth ions, remain poorly understood. Here, a thermal-electrostatic strategy is developed to achieve reversible and tunable europium ion intercalation that enables precise control over intercalation dynamics. This study investigates how temperature and voltage influence the intercalation of europium ions into bilayer graphene. Our results reveal the formation of a 2D europium layer and ionic state of intercalation europium within the graphene structure, providing fundamental insights into intercalation energetics. This work establishes a versatile platform for designing adaptive 2D heterostructure, engineering advanced materials and devices with unique electronic and optoelectronic properties.